Submarine
Overview
A submarine is a watercraft
Watercraft
A watercraft is a vessel or craft designed to move across or through water. The name is derived from the term "craft" which was used to describe all types of water going vessels...

 capable of independent operation below the surface of the water. It differs from a submersible
Submersible
A submersible is a small vehicle designed to operate underwater. The term submersible is often used to differentiate from other underwater vehicles known as submarines, in that a submarine is a fully autonomous craft, capable of renewing its own power and breathing air, whereas a submersible is...

, which has more limited underwater capability. The term submarine most commonly refers to a large crewed autonomous vessel; however, historically or colloquially, submarine can also refer to medium sized or smaller vessels (midget submarine
Midget submarine
A midget submarine is any submarine under 150 tons, typically operated by a crew of one or two but sometimes up to 6 or 8, with little or no on-board living accommodation...

s, wet sub
Wet sub
A wet sub is a type of underwater vehicle that does not provide a dry environment for its occupants. Usually, wet suited scuba divers will ride upon the device , although it can be designed to fully enclose its occupant to provide lower drag...

s), remotely operated vehicle
Remotely operated vehicle
A remotely operated vehicle is a tethered underwater vehicle. They are common in deepwater industries such as offshore hydrocarbon extraction. An ROV may sometimes be called a remotely operated underwater vehicle to distinguish it from remote control vehicles operating on land or in the air. ROVs...

s or robots
Autonomous Underwater Vehicle
An autonomous underwater vehicle is a robot which travels underwater without requiring input from an operator. AUVs constitute part of a larger group of undersea systems known as unmanned underwater vehicles, a classification that includes non-autonomous remotely operated underwater vehicles...

.

The word submarine was originally an adjective meaning "under the sea"; consequently other uses such as "submarine engineering" or "submarine cable
Submarine communications cable
A submarine communications cable is a cable laid on the sea bed between land-based stations to carry telecommunication signals across stretches of ocean....

" may not actually refer at all to the vessel.
Timeline

1776    World's first submarine attack: the American submersible craft ''Turtle'' attempts to attach a time bomb to the hull of British Admiral Richard Howe's flagship HMS ''Eagle'' in New York Harbor.

1863    American Civil War: The ''H. L. Hunley'', the first submarine to sink a ship, sinks during a test, killing its inventor, Horace L. Hunley.

1864    American Civil War: The {{Ship||H. L. Hunley|submarine|6}} becomes the first submarine to engage and sink a warship, the {{USS|Housatonic|1861|6}}.

1912    In Groton, Connecticut, the first diesel-powered submarine is commissioned.

1915    World War I: German submarine {{SMU|U-20}} sinks {{RMS|Lusitania}}, killing 1,198 people including 128 Americans. Public reaction to the sinking turns many formerly pro-Germans in the United States against the German Empire.

1915    US Navy salvage divers raise F-4, the first U.S. submarine sunk in accident.

1917    World War I: The United States breaks off diplomatic relations with Germany a day after the latter announced a new policy of unrestricted submarine warfare.

1918    A series of accidental collisions on a misty Scottish night leads to the loss of two Royal Navy submarines with over a hundred lives, and damage to another five British warships.

1930    The United Kingdom, Japan and the United States sign the London Naval Treaty regulating submarine warfare and limiting shipbuilding.

1939    The U.S. Navy submarine USS ''Squalus'' sinks off the coast of New Hampshire during a test dive, causing the death of 24 sailors and two civilian technicians. The remaining 32 sailors and one civilian naval architect are rescued the following day.

Encyclopedia
A submarine is a watercraft
Watercraft
A watercraft is a vessel or craft designed to move across or through water. The name is derived from the term "craft" which was used to describe all types of water going vessels...

 capable of independent operation below the surface of the water. It differs from a submersible
Submersible
A submersible is a small vehicle designed to operate underwater. The term submersible is often used to differentiate from other underwater vehicles known as submarines, in that a submarine is a fully autonomous craft, capable of renewing its own power and breathing air, whereas a submersible is...

, which has more limited underwater capability. The term submarine most commonly refers to a large crewed autonomous vessel; however, historically or colloquially, submarine can also refer to medium sized or smaller vessels (midget submarine
Midget submarine
A midget submarine is any submarine under 150 tons, typically operated by a crew of one or two but sometimes up to 6 or 8, with little or no on-board living accommodation...

s, wet sub
Wet sub
A wet sub is a type of underwater vehicle that does not provide a dry environment for its occupants. Usually, wet suited scuba divers will ride upon the device , although it can be designed to fully enclose its occupant to provide lower drag...

s), remotely operated vehicle
Remotely operated vehicle
A remotely operated vehicle is a tethered underwater vehicle. They are common in deepwater industries such as offshore hydrocarbon extraction. An ROV may sometimes be called a remotely operated underwater vehicle to distinguish it from remote control vehicles operating on land or in the air. ROVs...

s or robots
Autonomous Underwater Vehicle
An autonomous underwater vehicle is a robot which travels underwater without requiring input from an operator. AUVs constitute part of a larger group of undersea systems known as unmanned underwater vehicles, a classification that includes non-autonomous remotely operated underwater vehicles...

.

The word submarine was originally an adjective meaning "under the sea"; consequently other uses such as "submarine engineering" or "submarine cable
Submarine communications cable
A submarine communications cable is a cable laid on the sea bed between land-based stations to carry telecommunication signals across stretches of ocean....

" may not actually refer at all to the vessel. Submarine was in fact shortened from the proper term, "submarine boat", and is often further shortened to "sub" when the word is employed informally. Submarines should always be referred to as "boat
Boat
A boat is a watercraft of any size designed to float or plane, to provide passage across water. Usually this water will be inland or in protected coastal areas. However, boats such as the whaleboat were designed to be operated from a ship in an offshore environment. In naval terms, a boat is a...

s" rather than as "ship
Ship
Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...

s", regardless of their size. The English
English language
English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...

 term U-boat
U-boat
U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...

for a German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 submarine comes from the German
German language
German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....

 word for submarine, U-Boot, itself an abbreviation
Abbreviation
An abbreviation is a shortened form of a word or phrase. Usually, but not always, it consists of a letter or group of letters taken from the word or phrase...

 for Unterseeboot ("undersea boat").

Although experimental submarines had been built before, submarine design took off during the 19th century, and they were adopted by several different navies. Submarines were first widely used during World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

 (1914–1918) and now feature in many large navies
Navy
A navy is the branch of a nation's armed forces principally designated for naval and amphibious warfare; namely, lake- or ocean-borne combat operations and related functions...

. Military usage includes attacking enemy surface ships or submarines, aircraft carrier
Aircraft carrier
An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...

 protection, blockade
Blockade
A blockade is an effort to cut off food, supplies, war material or communications from a particular area by force, either in part or totally. A blockade should not be confused with an embargo or sanctions, which are legal barriers to trade, and is distinct from a siege in that a blockade is usually...

 running, ballistic missile submarines as part of a nuclear strike force, reconnaissance
Reconnaissance
Reconnaissance is the military term for exploring beyond the area occupied by friendly forces to gain information about enemy forces or features of the environment....

, conventional land attack (for example using a cruise missile
Cruise missile
A cruise missile is a guided missile that carries an explosive payload and is propelled, usually by a jet engine, towards a land-based or sea-based target. Cruise missiles are designed to deliver a large warhead over long distances with high accuracy...

), and covert insertion of special forces
Special forces
Special forces, or special operations forces are terms used to describe elite military tactical teams trained to perform high-risk dangerous missions that conventional units cannot perform...

. Civilian uses for submarines include marine science, salvage, exploration and facility inspection/maintenance. Submarines can also be modified to perform more specialized functions such as search-and-rescue missions or undersea cable repair. Submarines are also used in tourism, and for undersea archaeology.

Most large submarines comprise a cylindrical body with hemispherical (and/or conical) ends and a vertical structure, usually located amidships, which houses communications and sensing devices as well as periscopes. In modern submarines this structure is the "sail" in American usage, and "fin" in European usage. A "conning tower
Conning tower
A conning tower is a raised platform on a ship or submarine, often armored, from which an officer can con the vessel; i.e., give directions to the helmsman. It is usually located as high on the ship as practical, to give the conning team good visibility....

" was a feature of earlier designs: a separate pressure hull above the main body of the boat that allowed the use of shorter periscopes. There is a propeller (or pump jet) at the rear and various hydrodynamic control fins as well as ballast tanks. Smaller, deep diving and specialty submarines may deviate significantly from this traditional layout.

Submarines have one of the largest ranges of capabilities in any vessel, ranging from small autonomous examples to one- or two-person vessels operating for a few hours, to vessels which can remain submerged for 6 months such as the Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

n Typhoon class
Typhoon class submarine
The Project 941 or Akula, Russian "Акула" class submarine is a type of nuclear-powered ballistic missile submarine deployed by the Soviet Navy in the 1980s...

 - the biggest submarines ever built and in use. Submarines can work at greater depths than are survivable or practical for human diver
Underwater diving
Underwater diving is the practice of going underwater, either with breathing apparatus or by breath-holding .Recreational diving is a popular activity...

s. Modern deep diving submarines are derived from the bathyscaphe
Bathyscaphe
A bathyscaphe is a free-diving self-propelled deep-sea submersible, consisting of a crew cabin similar to a bathysphere, but suspended below a float rather than from a surface cable, as in the classic bathysphere design....

, which in turn was an evolution of the diving bell
Diving bell
A diving bell is a rigid chamber used to transport divers to depth in the ocean. The most common types are the wet bell and the closed bell....

.

Early history of submarines and the first submersibles

The first submersible with reliable information on its construction was built in 1620 by Cornelius Jacobszoon Drebbel
Cornelius Drebbel
Cornelis Jacobszoon Drebbel was the Dutch builder of the first navigable submarine in 1620. Drebbel was an innovator who contributed to the development of measurement and control systems, optics and chemistry....

, a Dutchman
Dutchman
Dutchman can refer to:* A person of Dutch descent.** A derogatory term for an Afrikaner from South Africa.* A Dutchman is a strip of material used to cover the join between two flats...

 in the service of James I of England
James I of England
James VI and I was King of Scots as James VI from 24 July 1567 and King of England and Ireland as James I from the union of the English and Scottish crowns on 24 March 1603...

. It was created to the standards of the design outlined by English mathematician William Bourne
William Bourne (mathematician)
William Bourne was an English mathematician, innkeeper and former Royal Navy gunner who invented the first navigable submarine and wrote important navigational manuals...

. It was propelled by means of oars. The precise nature of the submarine type is a matter of some controversy; some claim that it was merely a bell towed by a boat. Two improved types were tested in the Thames between 1620 and 1624. In 2002 a two-person version of Bourne's design was built for the BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...

 TV programme Building the Impossible by Mark Edwards
Mark Edwards (boatbuilder)
Mark Edwards is a traditional boatbuilder based at Richmond-upon-Thames, Surrey, England. He has constructed several significant reproductions of vintage boats....

, and successfully rowed under water at Dorney Lake
Dorney Lake
Dorney Lake is a purpose-built rowing lake in the United Kingdom. It is located at grid reference near the village of Dorney, Buckinghamshire, and near the towns of Windsor and Eton, close to the River Thames. The lake is privately owned and financed by Eton College, who have spent £17 million...

, Eton
Eton, Berkshire
Eton is a town and civil parish in Berkshire, England, lying on the opposite bank of the River Thames to Windsor and connected to it by Windsor Bridge. The parish also includes the large village of Eton Wick, 2 miles west of the town, and has a population of 4,980. Eton was in Buckinghamshire until...

.

Though the first submersible vehicles were tools for exploring under water, it did not take long for inventors to recognize their military potential. The strategic advantages of submarines were set out by Bishop John Wilkins
John Wilkins
John Wilkins FRS was an English clergyman, natural philosopher and author, as well as a founder of the Invisible College and one of the founders of the Royal Society, and Bishop of Chester from 1668 until his death....

 of Chester
Chester
Chester is a city in Cheshire, England. Lying on the River Dee, close to the border with Wales, it is home to 77,040 inhabitants, and is the largest and most populous settlement of the wider unitary authority area of Cheshire West and Chester, which had a population of 328,100 according to the...

, England, in Mathematicall Magick in 1648:

  1. Tis private: a man may thus go to any coast in the world invisibly, without discovery or prevented in his journey.
  2. Tis safe, from the uncertainty of Tides, and the violence of Tempests, which do never move the sea above five or six paces deep. From Pirates and Robbers which do so infest other voyages; from ice and great frost, which do so much endanger the passages towards the Poles.
  3. It may be of great advantages against a Navy of enemies, who by this may be undermined in the water and blown up.
  4. It may be of special use for the relief of any place besieged by water, to convey unto them invisible supplies; and so likewise for the surprisal of any place that is accessible by water.
  5. It may be of unspeakable benefit for submarine experiments.



First military submarines

The first military submarine was Turtle
Turtle (submarine)
The Turtle was the world's first submersible with a documented record of use in combat. It was built in Old Saybrook, Connecticut in 1775 by American Patriot David Bushnell as a means of attaching explosive charges to ships in a harbor...

 (1775), a hand-powered acorn-shaped device designed by the American David Bushnell
David Bushnell
David Bushnell , of Westbrook, Connecticut, was an American inventor during the Revolutionary War. He is credited with creating the first submarine ever used in combat, while studying at Yale University in 1775. He called it the Turtle because of its look in the water...

 to accommodate a single person. It was the first verified submarine capable of independent underwater operation and movement, and the first to use screw
Propeller
A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the airfoil-shaped blade, and a fluid is accelerated behind the blade. Propeller dynamics can be modeled by both Bernoulli's...

s for propulsion. During the American Revolutionary War
American Revolutionary War
The American Revolutionary War , the American War of Independence, or simply the Revolutionary War, began as a war between the Kingdom of Great Britain and thirteen British colonies in North America, and ended in a global war between several European great powers.The war was the result of the...

, Turtle (operated by Sgt. Ezra Lee, Continental Army) tried and failed to sink the British warship HMS Eagle
HMS Eagle (1774)
HMS Eagle was a 64-gun third rate ship of the line of the Royal Navy, launched on 2 May 1774 at Rotherhithe.On 7 September 1776, the experimental American submarine Turtle, under the guidance of Army volunteer Sergeant Ezra Lee, attacked HMS Eagle, which was moored off what is today called Liberty...

, flagship of the blockaders in New York
New York City
New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...

 harbor on September 7, 1776.

In 1800, France built a human-powered submarine designed by American Robert Fulton
Robert Fulton
Robert Fulton was an American engineer and inventor who is widely credited with developing the first commercially successful steamboat...

, the Nautilus. The French eventually gave up on the experiment in 1804, as did the British when they later considered Fulton's submarine design.

During the War of 1812
War of 1812
The War of 1812 was a military conflict fought between the forces of the United States of America and those of the British Empire. The Americans declared war in 1812 for several reasons, including trade restrictions because of Britain's ongoing war with France, impressment of American merchant...

, in 1814, Silas Halsey lost his life while using a submarine in an unsuccessful attack on a British warship stationed in New London harbor
New London, Connecticut
New London is a seaport city and a port of entry on the northeast coast of the United States.It is located at the mouth of the Thames River in New London County, southeastern Connecticut....

.

The Submarino Hipopótamo was the first submarine in South America built and tested in Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...

 on September 18, 1837. It was designed by Jose Rodriguez Lavandera, who successfully crossed the Guayas River
Guayas River
The Guayas River is a river in western Ecuador. It gives name to the Guayas Province, and it is the most important river in South America that does not flow into the Atlantic Ocean or any of its seas. Its total length, including the Daule River, is 389 km.-Course:The Guayas River has one of...

 in Guayaquil
Guayaquil
Guayaquil , officially Santiago de Guayaquil , is the largest and the most populous city in Ecuador,with about 2.3 million inhabitants in the city and nearly 3.1 million in the metropolitan area, as well as that nation's main port...

 accompanied by Jose Quevedo. Rodriguez Lavandera had enrolled in the Ecuadorian Navy in 1823, becoming a Lieutenant by 1830. The Hipopotamo crossed the Guayas on two more occasions, but it was then abandoned because of lack of funding and interest from the government. Today, few engravings and a scale model of the original design is preserved by the Maritime Museum of the Ecuadorian Navy.

In 1851, a Bavarian artillery corporal, Wilhelm Bauer
Wilhelm Bauer
Wilhelm Bauer was the German inventor and engineer, who built several hand-powered submarines.-Biography:...

, took a submarine designed by him called the Brandtaucher
Brandtaucher
Brandtaucher was a submersible designed by the German inventor and engineer Wilhelm Bauer and built by Schweffel & Howaldt in Kiel for Schleswig-Holstein's Flotilla in 1850....

(incendiary-diver), which sank on its first test dive in Kiel
Kiel
Kiel is the capital and most populous city in the northern German state of Schleswig-Holstein, with a population of 238,049 .Kiel is approximately north of Hamburg. Due to its geographic location in the north of Germany, the southeast of the Jutland peninsula, and the southwestern shore of the...

 Harbour—but its three crewmen managed to escape, after flooding the vessel, which allowed the inside pressure to equalize. This submarine was built by August Howaldt
August Howaldt
August Ferdinand Howaldt was a German engineer and ship builder.-Biography:Born in Braunschweig, the son of the silversmith David Ferdinand Howaldt, with whom he got his first practice working in metal, Howaldt made an apprenticeship in Hamburg and became a practical mechanicus.In 1838 he moved to...

 and powered by a treadwheel
Treadwheel
A treadwheel is a form of animal engine typically powered by humans. It may resemble a water wheel in appearance, and can be worked either by a human treading paddles set into its circumference , or by a human or animal standing inside it .Uses of treadwheels included raising water, to power...

. The submarine was re-discovered during a dredging operation 1887, and was raised sixteen years later. The vessel is on display in a museum in Dresden.

The submarine Flach
Flach (submarine)
Flach was the first submarine designed and built in Chile in 1866. It is currently missing.-History:The Flach was built in 1866 at the request of the Chilean government, by Karl Flach, a German engineer and immigrant...

 was commissioned in 1865 by the Chilean government during the war of Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

 and Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....

 against Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

 (1864–1866). It was built by the German engineer Karl Flach. The submarine sank during tests in Valparaiso
Valparaíso
Valparaíso is a city and commune of Chile, center of its third largest conurbation and one of the country's most important seaports and an increasing cultural center in the Southwest Pacific hemisphere. The city is the capital of the Valparaíso Province and the Valparaíso Region...

 bay on May 3, 1866, with the entire eleven-man crew.

Submarines in the American Civil War

During the American Civil War
American Civil War
The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...

 both sides successfully built working submarines. The Confederate States of America
Confederate States of America
The Confederate States of America was a government set up from 1861 to 1865 by 11 Southern slave states of the United States of America that had declared their secession from the U.S...

 submarines were all designed to attack the Union blockade
Union blockade
The Union Blockade, or the Blockade of the South, took place between 1861 and 1865, during the American Civil War, when the Union Navy maintained a strenuous effort on the Atlantic and Gulf Coast of the Confederate States of America designed to prevent the passage of trade goods, supplies, and arms...

 of Southern ports. Two operational unnamed Confederate submarines were spotted during the latter half of 1861, one in the James River
James River
The James River may refer to:Rivers in the United States and their namesakes* James River * James River , North Dakota, South Dakota* James River * James River * James River...

 in Virginia
Virginia
The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...

 and another in New Orleans. The United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 was first interested in submarines as a way to clear obstacles. Interest in attack submarines began at least by May 1861, when French engineer Brutus de Villeroi
Brutus de Villeroi
Brutus de Villeroi was a French engineer of the 19th century, born as Brutus Villeroi in the city of Tours and soon moved to Nantes, who developed some of the first operational submarines, and the first submarine of the United States Navy, the Alligator in 1862.-Villeroi's first submarine :In...

 tested an early submarine design in Philadelphia harbor in what may have been a effort to attract the Navy's attention. Most Confederate submarines were built under the auspices of the Confederate Secret Service rather than the Confederate Navy, with only three being well known and documented. Others, both Confederate and Union, are known to have existed but their names and designs have escaped the historical record. In all, evidence indicates that a combined total of over twenty operational submarines were built by both sides during the conflict.

First launched on May 1, 1862, the Villeroi-designed Alligator was the first U.S. Navy submarine. It was also the first to feature compressed air for an air supply and an air filtration system. Initially propelled by sixteen hand-powered paddles protruding from the sides, it was converted after six months to a screw propeller powered by a hand crank. At 47 feet (14.3 m) long and about 4 feet (1.2 m) in diameter, the Alligator was the largest of the documented American Civil War submarines. It was lost in a storm off Cape Hatteras
Cape Hatteras
Cape Hatteras is a cape on the coast of North Carolina. It is the point that protrudes the farthest to the southeast along the northeast-to-southwest line of the Atlantic coast of North America...

 on April 1, 1863 while under tow to its first combat deployment at Charleston.

The first documented Confederate submarine was the New Orleans-built Pioneer
Pioneer (submarine)
Pioneer was the first of three submarines privately developed and paid for by Horace Lawson Hunley, James McClintock and Baxter Watson.Hunley, McClintock and Watson built Pioneer in New Orleans, Louisiana...

. It was 30 feet (9 m) long. This submarine sank a target schooner
Schooner
A schooner is a type of sailing vessel characterized by the use of fore-and-aft sails on two or more masts with the forward mast being no taller than the rear masts....

 using a towed mine during tests on Lake Pontchartrain
Lake Pontchartrain
Lake Pontchartrain is a brackish estuary located in southeastern Louisiana. It is the second-largest inland saltwater body of water in the United States, after the Great Salt Lake in Utah, and the largest lake in Louisiana. As an estuary, Pontchartrain is not a true lake.It covers an area of with...

 in February 1862. It was never used in combat, having been scuttled
Scuttling
Scuttling is the act of deliberately sinking a ship by allowing water to flow into the hull.This can be achieved in several ways—valves or hatches can be opened to the sea, or holes may be ripped into the hull with brute force or with explosives...

 by Confederate forces before New Orleans was captured by the Union in April 1862. The Bayou St. John Confederate Submarine
Bayou St. John Confederate Submarine
The Bayou St. John Confederate Submarine is an early military submarine built for use by the Confederate States of America during the American Civil War.-Description:...

 is another Louisiana-built submarine that is contemporaneous with the Pioneer, although no history is known. It is now on display at the Louisiana State Museum
Louisiana State Museum
The Louisiana State Museum , founded in New Orleans in 1906 and still headquartered there, is a complex of National Historic Landmarks housing thousands of artifacts and works of art reflecting Louisiana's legacy of historic events and cultural diversity....

.

The second documented Confederate submarine was the American Diver
American Diver
American Diver, also known as the Pioneer II, was a prototype submarine built for the Confederate States of America military. It was the first successor to the Pioneer. The Diver was invented and built by the same consortium that built the Pioneer in New Orleans. It was composed of Horace Lawson...

, also known as the Pioneer II, built in Mobile, Alabama
Mobile, Alabama
Mobile is the third most populous city in the Southern US state of Alabama and is the county seat of Mobile County. It is located on the Mobile River and the central Gulf Coast of the United States. The population within the city limits was 195,111 during the 2010 census. It is the largest...

. It was initially designed to be propelled by an electric motor
Electric motor
An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...

 but this proved to be too weak. A steam engine
Steam engine
A steam engine is a heat engine that performs mechanical work using steam as its working fluid.Steam engines are external combustion engines, where the working fluid is separate from the combustion products. Non-combustion heat sources such as solar power, nuclear power or geothermal energy may be...

 was installed next, but also proved to be insufficient. Finally, a hand-cranked propeller was installed. The Diver was 36 feet (11 m) long with a 3 foot (0.9144 m) beam
Beam (nautical)
The beam of a ship is its width at the widest point. Generally speaking, the wider the beam of a ship , the more initial stability it has, at expense of reserve stability in the event of a capsize, where more energy is required to right the vessel from its inverted position...

. It was lost during a storm while under tow during trials in Mobile Bay
Mobile Bay
Mobile Bay is an inlet of the Gulf of Mexico, lying within the state of Alabama in the United States. Its mouth is formed by the Fort Morgan Peninsula on the eastern side and Dauphin Island, a barrier island on the western side. The Mobile River and Tensaw River empty into the northern end of the...

 in late February 1863.

The third documented Confederate submarine was H. L. Hunley
H. L. Hunley (submarine)
H. L. Hunley was a submarine of the Confederate States of America that played a small part in the American Civil War, but a large role in the history of naval warfare. The Hunley demonstrated both the advantages and the dangers of undersea warfare...

, named for one of its financiers, Horace Lawson Hunley
Horace Lawson Hunley
Horace Lawson Hunley , was a Confederate marine engineer during the American Civil War. He developed early hand-powered submarines, the most famous of which was posthumously named for him, H. L...

. Also built in Mobile, she was launched in July 1863. She was 39.5 feet (12 m) long with a 3.83 feet (1.2 m) beam. Hunley was designed to be propelled by a hand-crank from the beginning and could accommodate eight men to turn the hand-crank, as opposed to four men for Diver, and was armed with a spar torpedo
Spar torpedo
A spar torpedo is a weapon consisting of a bomb placed at the end of a long pole, or spar, and attached to a boat. The weapon is used by running the end of the spar into the enemy ship. Spar torpedoes were often equipped with a barbed spear at the end, so it would stick to wooden hulls...

. The submarine had to approach an enemy vessel, attach the explosive with a barb, move away, and then detonate it. Hunley proved to be hazardous to operate, and had no air supply other than what was contained in the hull. On three occasions, she sank. On August 29, 1863, five out of the nine crew members drowned during a trial run. The second incident occurred on October 15, 1863, when all eight people on board, including Hunley, drowned during a diving exercise. Then, on February 17, 1864, the salvaged and renovated vessel sank USS Housatonic
USS Housatonic (1861)
The first USS Housatonic was a screw sloop-of-war of the United States Navy, named for the Housatonic River of New England which rises in Berkshire County, Massachusetts, and flows southward into Connecticut before emptying into Long Island Sound a little east of Bridgeport, Connecticut...

 off Charleston Harbor. Soon after signaling success, the submarine sank due to unknown cause; again the entire eight-man crew drowned. Submarines did not have a major impact on the outcome of the war, but did portend their future importance to, and increased interest in their use in, naval warfare. The location of Hunley was unknown until 1995, and she was raised in 2000. The sinking of Housatonic by Hunley was the first successful submarine attack on a warship.

Mechanically powered submarines, late 19th Century

The first submarine not relying on human power for propulsion was the French Plongeur (Diver), launched in 1863, and using compressed air at 180 psi (1241 kPa
Pascal (unit)
The pascal is the SI derived unit of pressure, internal pressure, stress, Young's modulus and tensile strength, named after the French mathematician, physicist, inventor, writer, and philosopher Blaise Pascal. It is a measure of force per unit area, defined as one newton per square metre...

).

The first combustion-powered submarine was Ictineo II
Ictineo II
Ictineo II was a pioneering submarine launched in 1864 by Spanish inventor Narcís Monturiol i Estarriol, and was the first combustion engine-driven submarine, propelled by an early form of air-independent propulsion...

, designed in Catalonia, Spain by Narcís Monturiol
Narcís Monturiol i Estarriol
Narcís Monturiol Estarriol was a Spanish Catalan intellectual, artist and engineer. He was the inventor of the first combustion engine-driven submarine, which was propelled by an early form of air-independent propulsion....

. Originally launched in 1864 as human-powered, propelled by 16, it was converted to peroxide propulsion and steam in 1867. The 14 m (45.9 ft)-long craft was designed for a crew of two, could dive to 30 m (98.4 ft), and demonstrated dives of two hours. On the surface it ran on a steam engine, but underwater such an engine would quickly consume the submarine's oxygen, so Monturiol invented an air-independent propulsion system
Air-independent propulsion
Air-independent propulsion is a term that encompasses technologies which allow a submarine to operate without the need to surface or use a snorkel to access atmospheric oxygen. The term usually excludes the use of nuclear power, and describes augmenting or replacing the diesel-electric propulsion...

. While the air-independent power system drove the screw, the chemical process driving it also released oxygen into the hull for the crew and an auxiliary steam engine. Monturiol's fully functional, double hulled vessels also solved pressure and buoyancy control problems that had bedeviled earlier designs.

In 1870, the French writer Jules Verne
Jules Verne
Jules Gabriel Verne was a French author who pioneered the science fiction genre. He is best known for his novels Twenty Thousand Leagues Under the Sea , A Journey to the Center of the Earth , and Around the World in Eighty Days...

, inspired by the recent efforts of Monturiol and of his own navy, published the science fiction
Science fiction
Science fiction is a genre of fiction dealing with imaginary but more or less plausible content such as future settings, futuristic science and technology, space travel, aliens, and paranormal abilities...

 classic 20,000 Leagues under the Sea
Twenty Thousand Leagues Under the Sea
Twenty Thousand Leagues Under the Sea is a classic science fiction novel by French writer Jules Verne published in 1870. It tells the story of Captain Nemo and his submarine Nautilus as seen from the perspective of Professor Pierre Aronnax...

, which concerns the adventures of a maverick inventor of the Nautilus
Nautilus (Verne)
The Nautilus is the fictional submarine featured in Jules Verne's novels Twenty Thousand Leagues Under the Sea and The Mysterious Island . Verne named the Nautilus after Robert Fulton's real-life submarine Nautilus...

, a submarine more advanced than any at the time. An international success, the story encouraged inventors around the world to work towards making such a vehicle a reality.

In 1879, the Peruvian government, during the War of the Pacific
War of the Pacific
The War of the Pacific took place in western South America from 1879 through 1883. Chile fought against Bolivia and Peru. Despite cooperation among the three nations in the war against Spain, disputes soon arose over the mineral-rich Peruvian provinces of Tarapaca, Tacna, and Arica, and the...

, commissioned and built the fully operational submarine Toro Submarino
Toro Submarino
The Toro Submarino was a Peruvian submarine developed during the War of the Pacific. While it was completely operational, the submarine never saw action before the end of the war, when it was scuttled to prevent its capture by Chilean troops.-Development:In 1864, an overseas German civil engineer...

. It never saw military action before being scuttled by the Peruvians after their defeat in the war to prevent its capture by the Chileans.

The first submarine to be mass-produced was human-powered. It was the submarine of the Polish inventor Stefan Drzewiecki
Stefan Drzewiecki
Stefan Drzewiecki was a Polish scientist, journalist, engineer, constructor and inventor, working in Russia and France....

—50 units were built in 1881 for the Russian government. In 1884 the same inventor built an electric-powered submarine.

Discussions between the English clergyman and inventor George Garrett and the industrially and commercially adept Swede Thorsten Nordenfelt
Thorsten Nordenfelt
Thorsten Nordenfelt , was a Swedish inventor and industrialist.Nordenfelt was born in Örby outside Kinna, Sweden, the son of a colonel. The surname was and is often spelt Nordenfeldt, though Thorsten and his brothers always spelt it Nordenfelt, and the 1881 Census shows it as Nordenfelt...

 led to a series of steam-powered submarines. The first was the Nordenfelt I, a 56 tonne, 19.5 metre (64 ft) vessel similar to Garret's ill-fated Resurgam
Resurgam
Resurgam is the name given to two early Victorian submarines designed and built by Reverend George Garrett as a weapon to penetrate the chain netting placed around ship hulls to defend against attack by torpedo vessels....

(1879), with a range of 240 kilometres (150 mi, 130 nm), armed with a single torpedo
Torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

, in 1885. Like Resurgam, Nordenfelt I operated on the surface by steam, then shut down its engine to dive. While submerged the submarine released pressure generated when the engine was running on the surface to provide propulsion for some distance underwater. Greece
Greece
Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....

, fearful of the return of the Ottomans
Ottoman Empire
The Ottoman EmpireIt was usually referred to as the "Ottoman Empire", the "Turkish Empire", the "Ottoman Caliphate" or more commonly "Turkey" by its contemporaries...

, purchased it. Nordenfelt then built Nordenfelt II (Abdülhamid
Ottoman submarine Abdül Hamid
Submarine Abdül Hamid was the first submarine built in the United Kingdom, being constructed in 1886 at the Barrow Shipyard. It was bought and put in service by the Ottoman Navy and named after Sultan Abdülhamid II...

) in 1886 and Nordenfelt III (Abdülmecid) in 1887, a pair of 30 metre (100 ft) submarines with twin torpedo tube
Torpedo tube
A torpedo tube is a device for launching torpedoes. There are two main types of torpedo tube: underwater tubes fitted to submarines and some surface ships, and deck-mounted units installed aboard surface vessels...

s, for the Ottoman navy. Abdülhamid became the first submarine in history to fire a torpedo submerged. Nordenfelt's efforts culminated in 1887 with Nordenfelt IV which had twin motors and twin torpedoes. It was sold to the Russians, but proved unstable, ran aground, and was scrapped.

Two submarines, both launched in September 1888, marked the maturing of naval submarine technology.

One was the Peral Submarine
Peral Submarine
The Peral was the first electric battery powered submarine. Its operational abilities has led some to call it the first U-boat. -Conception:...

, launched by the Spanish Navy. It had two torpedoes, new air systems, hull shape, propeller, and cruciform external controls anticipating much later designs. Peral was the first all-electrical powered submarine. After two years of trials the project was scrapped by naval officialdom that cited concerns over the short range permitted by its batteries.

The other was the Gymnote, launched by the French Navy. Gymnote was also an electrically powered and fully functional military submarine. It completed over 2,000 successful dives using a 204-cell battery. Although she was scrapped for her limited range her side hydroplanes became the standard for future submarine designs.

Many more designs were built at this time by various inventors, but submarines were not put into service by navies until 1900.

End of the 19th century to the Russo-Japanese War

The turn of the 20th century marked a pivotal time in the development of submarines, with a number of important technologies making their debut, as well as the widespread adoption and fielding of submarines by a number of nations. Diesel electric propulsion would become the dominant power system and equipment such as the periscope would become standardized. Large numbers of experiments were done by countries on effective tactics and weapons for submarines, all of which would culminate in them making a large impact on the coming World War I.

In 1896, the Irish-American inventor John Philip Holland
John Philip Holland
John Philip Holland was an Irish engineer who developed the first submarine to be formally commissioned by the U.S...

 designed submarines that, for the first time, made use of internal combustion engine
Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...

s on the surface and electric battery power submerged. Fenian Ram
Fenian Ram
Fenian Ram is a submarine designed by John Philip Holland for use by the Fenian Brotherhood, American counterpart to the Irish Republican Brotherhood, against the British...

, in 1881, was world's first successful submarine. Holland VI was launched on May 17, 1897 at Navy Lt. Lewis Nixon
Lewis Nixon (naval architect)
Lewis Nixon I was a naval architect, shipbuilding executive, public servant, and political activist. He designed the United States' first modern battleships, and supervised the construction of its first modern submarines, all before his 40th birthday. He was briefly the leader of Tammany Hall...

's Crescent Shipyard
Crescent Shipyard
Crescent Shipyard, located in Elizabeth, New Jersey, built a number of ships for the United States Navy and allied nations as well during their production run, which lasted about ten years while under the Crescent name and banner. Production of these ships began before the Spanish-American war and...

 of Elizabeth, New Jersey. On April 11, 1900 the United States Navy purchased the revolutionary Holland VI and renamed it , America's first commissioned submarine. (John P. Holland's company, the Holland Torpedo Boat Company/Electric Boat Company became General Dynamics
General Dynamics
General Dynamics Corporation is a U.S. defense conglomerate formed by mergers and divestitures, and as of 2008 it is the fifth largest defense contractor in the world. Its headquarters are in West Falls Church , unincorporated Fairfax County, Virginia, in the Falls Church area.The company has...

' Cold War
Cold War
The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...

 progeny and is the builder of technologically advanced submarines today).

Commissioned in June 1900, the French steam and electric Narval introduced the classic double-hull design, with a pressure hull inside the outer shell. These 200-ton ships had a range of over 100 miles (160 km) underwater. The French submarine Aigrette in 1904 further improved the concept by using a diesel rather than a gasoline engine for surface power. Large numbers of these submarines were built, with seventy-six completed before 1914.

Submarines during the Russo-Japanese War

The first mechanically powered series of submarines to be put into service by navies, which included Great Britain, Japan, Russia, and the United States, were the Holland submersibles built by Irish designer John Philip Holland
John Philip Holland
John Philip Holland was an Irish engineer who developed the first submarine to be formally commissioned by the U.S...

 in 1900. Several of each of them were retained in both the Imperial Russian and Japanese Navies during the Russo-Japanese War
Russo-Japanese War
The Russo-Japanese War was "the first great war of the 20th century." It grew out of rival imperial ambitions of the Russian Empire and Japanese Empire over Manchuria and Korea...

 in 1904-1905.

The Imperial Japanese Navy
Imperial Japanese Navy
The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...

 (IJN) started their submarine service with five Holland Type VII submarines purchased from the Electric Boat Company in 1904. The five vessels were delivered in sections, arriving in Japan on 14 June 1904. After re-assembly, the five Hollands were ready for combat operations in August 1905, but the Russo-Japanese War was nearing its end by that date, and no IJN submarines would see action in that war.

The first submarines built in Japan were constructed by Kawasaki
Kawasaki Shipbuilding Corporation
-External links:*...

 beginning in 1904. The Kaigun Holland Type #6 and #7 were each launched on 28 September but a year apart, in 1905 and 1906 respectively. Both submarines were modified versions of the original imported Hollands. However, while the original vessels had each displaced over a 100 tons submerged, and were approximately 67' long and 11' wide; the Kawasaki boats displaced only 63/95 tons submerged, and measured 73'/84' by 7' respectively for the number 6 & 7 submarines. The Kawasaki machines had increased horse-power by 1/2, and reduced fuel consumption by 1/4, but could only launch one 18" torpedo and carried 14 men, while the Hollands could fire two 18" torpedoes and operate with only 13 crewmen. The Kaigun Holland #6 submarine has been preserved as a memorial at Kure
Kure
Kure can refer to:*KURE, a radio station in Ames, Iowa*Kure Software Koubou, Japanese video game development company*Kure, Hiroshima , a city in Hiroshima prefecture, Japan**Kure Line, a rail line in the city...

, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

.

The Imperial Russian Navy
Imperial Russian Navy
The Imperial Russian Navy refers to the Tsarist fleets prior to the February Revolution.-First Romanovs:Under Tsar Mikhail Feodorovich, construction of the first three-masted ship, actually built within Russia, was completed in 1636. It was built in Balakhna by Danish shipbuilders from Holstein...

 (IRN) preferred the German constructed submersibles built by the Germaniawerft shipyards out of Kiel
Kiel
Kiel is the capital and most populous city in the northern German state of Schleswig-Holstein, with a population of 238,049 .Kiel is approximately north of Hamburg. Due to its geographic location in the north of Germany, the southeast of the Jutland peninsula, and the southwestern shore of the...

. In 1903 Germany successfully completed its first fully functional engine-powered submarine, the Forelle (Trout
Trout
Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...

). This vessel was sold to Russia in 1904 and shipped via the Trans-Siberian Railway
Trans-Siberian Railway
The Trans-Siberian Railway is a network of railways connecting Moscow with the Russian Far East and the Sea of Japan. It is the longest railway in the world...

 to the combat zone during the Russo-Japanese War. In 1901 two IRN Lieutenants, Kolbasieff and Kuteinoff designed and built the electric submarine Piotr Koschka which was operated by bicycle
Bicycle
A bicycle, also known as a bike, pushbike or cycle, is a human-powered, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A person who rides a bicycle is called a cyclist, or bicyclist....

 pedals
Bicycle pedal
A bicycle pedal is the part of a bicycle that the rider pushes with their foot to propel the bicycle. It provides the connection between the cyclist's foot or shoe and the crank allowing the leg to turn the bottom bracket spindle and propel the bicycle's wheels...

, but no other versions were built. During the final weeks of the Port Arthur
Siege of Port Arthur
The Siege of Port Arthur , 1 August 1904 – 2 January 1905, the deep-water port and Russian naval base at the tip of the Liaotung Peninsula in Manchuria, was the longest and most violent land battle of the Russo-Japanese War....

 siege in 1904, the IRN attempted to place the Piotr Koschka into operation, her bicycle pedals having been replaced by an automobile engine. But the attempt to deploy the submarine into the Port Arthur battle was unsuccessful.

A prototype version of the Plunger-class
Plunger class submarine
The Plunger-class was an early class of United States Navy submarines, used primarily as training vessels for the newly formed "silent service" to familiarize navy personnel with the performance and operations of such craft. Most of these "A-class" submarines ended up being stationed in the...

 or A-class submarines, the Fulton, was developed at Nixon's Crescent Shipyard for the United States Navy before the construction of the A-class submarines there in 1901. A naval architect and shipbuilder from the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, Arthur Leopold Busch
Arthur Leopold Busch
Arthur Leopold Busch or Du Busc was a British-born American naval architect responsible for the development of the United States Navy's first submarines.-Career:...

, superintended the development of these first submarines for Holland's company. However the Fulton was never purchased by the U.S. Navy and was eventually sold to the Imperial Russian Navy
Imperial Russian Navy
The Imperial Russian Navy refers to the Tsarist fleets prior to the February Revolution.-First Romanovs:Under Tsar Mikhail Feodorovich, construction of the first three-masted ship, actually built within Russia, was completed in 1636. It was built in Balakhna by Danish shipbuilders from Holstein...

 during the Russo-Japanese War
Russo-Japanese War
The Russo-Japanese War was "the first great war of the 20th century." It grew out of rival imperial ambitions of the Russian Empire and Japanese Empire over Manchuria and Korea...

 of 1904-1905. Two other A-class vessels were built on the West Coast of (USA) at Mare Island Naval Shipyard
Mare Island Naval Shipyard
The Mare Island Naval Shipyard was the first United States Navy base established on the Pacific Ocean. It is located 25 miles northeast of San Francisco in Vallejo, California. The Napa River goes through the Mare Island Strait and separates the peninsula shipyard from the main portion of the...

/Union Iron Works
Union Iron Works
Union Iron Works, located in San Francisco, California, on the southeast waterfront, was a central business within the large industrial zone of Potrero Point, for four decades at the end of the nineteenth and beginning of the twentieth centuries.-History:...

 circa 1901. In 1902, Holland received a patent for his persistent pursuit to perfect the underwater naval craft. By this time, Holland was no longer in control of the day-to-day operations at Electric Boat, as others were now at the helm of the company he once founded. The acumen of business were now in control of these operations as Holland was forced to step down. His resignation from the company was to be effective as of April 1904.

Due to the blockade at Port Arthur, Russia sent the remainder of their submarines to Vladivostok
Vladivostok
The city is located in the southern extremity of Muravyov-Amursky Peninsula, which is about 30 km long and approximately 12 km wide.The highest point is Mount Kholodilnik, the height of which is 257 m...

, where by 1 January 1905 there were seven boats, enough to create the world's first "operational submarine fleet." The new submarine fleet sent out its first patrol on 14 February, usually lasting for about 24 hours. The first confrontation with Japanese warships occurred on 29 April 1905 when the IRN sub Som was fired upon by IJN torpedo boats, but then withdrew.

In 1904, the Imperial Russian Navy ordered several more submersibles from the Kiel shipyard, submarines from the Karp
Karp
-People:*Algo Kärp , Estonian cross-country skier*Barrie Karp , U.S. philosopher and visual artist*Bob Karp , U.S. comics writer*Brad S. Karp , U.S. litigator*Carol Karp , U.S...

 class. One sample of which was modified and improved, and commissioned into the Imperial German Navy in 1906 as its first U-Boat
U-boat
U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...

, the . U-1 was retired from service in 1919, and is currently preserved and on display in the Deutsches Museum
Deutsches Museum
The Deutsches Museum in Munich, Germany, is the world's largest museum of technology and science, with approximately 1.5 million visitors per year and about 28,000 exhibited objects from 50 fields of science and technology. The museum was founded on June 28, 1903, at a meeting of the Association...

 in Munich.

Submarines during World War I

Military submarines first made a significant impact in World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. Forces such as the U-boat
U-boat
U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...

s of Germany saw action in the First Battle of the Atlantic, and were responsible for the sinking of Lusitania
RMS Lusitania
RMS Lusitania was a British ocean liner designed by Leonard Peskett and built by John Brown and Company of Clydebank, Scotland. The ship entered passenger service with the Cunard Line on 26 August 1907 and continued on the line's heavily-traveled passenger service between Liverpool, England and New...

, which was sunk as a result of unrestricted submarine warfare
Unrestricted submarine warfare
Unrestricted submarine warfare is a type of naval warfare in which submarines sink merchantmen without warning, as opposed to attacks per prize rules...

 and is often cited among the reasons for the entry of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 into the war.

In August 1914, a flotilla of ten U-boats sailed from their base in Heligoland
Heligoland
Heligoland is a small German archipelago in the North Sea.Formerly Danish and British possessions, the islands are located in the Heligoland Bight in the south-eastern corner of the North Sea...

 to attack Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 warships in the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

 in the first submarine war patrol in history.
Their aim was to sink capital ships of the British Grand Fleet, and so reduce the Grand Fleet's numerical superiority over the German High Seas Fleet. With much depending more on luck than strategy, the first sortie was not a success. Only one attack was carried out, when U-15 fired a torpedo (which missed) at HMS Monarch
HMS Monarch (1911)
HMS Monarch was an Orion-class battleship of the Royal Navy. She served in the 2nd Battle Squadron of the Grand Fleet in World War I, and fought at the Battle of Jutland, 31 May 1916, suffering no damage....

, while two of the ten U-boats were lost. The U-9 had better luck. On 22 September 1914 while patrolling the Broad Fourteens
Broad Fourteens
thumb|200px|right|The Broad Fourteens on a map by Delisle The Broad Fourteens is an area of the southern North Sea that is fairly consistently fourteen fathoms deep...

, a region of the southern North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

, U-9 found a squadron of three obsolescent British Cressy-class
Cressy class cruiser
The Cressy class cruiser was a class of six armoured cruisers launched between December 1899 and May 1901, for the Royal Navy.-Service:...

 armoured cruisers (HMS Aboukir
HMS Aboukir (1900)
HMS Aboukir was a Cressy-class armoured cruiser. She was built by Fairfield Shipbuilding & Engineering Co Ltd, Govan, Scotland in 1902.-First World War:...

, HMS Hogue
HMS Hogue (1900)
HMS Hogue was a Cressy-class armoured cruiser in the Royal Navy. Hogue was sunk by the German U-boat U-9 on 22 September 1914.-Service history:...

, and HMS Cressy
HMS Cressy (1899)
HMS Cressy was a Cressy-class armoured cruiser in the Royal Navy. Cressy was sunk by the German U-boat U-9 in September 1914.-Service history:...

), which were assigned to prevent German surface vessels from entering the eastern end of the English Channel
English Channel
The English Channel , often referred to simply as the Channel, is an arm of the Atlantic Ocean that separates southern England from northern France, and joins the North Sea to the Atlantic. It is about long and varies in width from at its widest to in the Strait of Dover...

. She fired all six of her torpedoes, reloading while submerged, and sank all three in less than an hour.

The U-boats' ability to function as practical war machines relied on new tactics, their numbers, and submarine technologies such as combination diesel-electric power system developed in the preceding years. More submersibles than true submarines, U-boats operated primarily on the surface using regular engines, submerging occasionally to attack under battery power. They were roughly triangular in cross-section, with a distinct keel
Keel
In boats and ships, keel can refer to either of two parts: a structural element, or a hydrodynamic element. These parts overlap. As the laying down of the keel is the initial step in construction of a ship, in British and American shipbuilding traditions the construction is dated from this event...

 to control rolling while surfaced, and a distinct bow. During World War I more than 5,000 Allied ships were sunk by U-boats.

Interwar developments

Various new submarine designs were developed during the interwar years. Among the most notable ones were submarine aircraft carrier
Submarine aircraft carrier
Submarine aircraft carriers are submarines equipped with fixed wing aircraft for observation or attack missions. These submarines saw their most extensive use during World War II, although their operational significance remained rather small...

s, equipped with a waterproof hangar and steam catapult to launch and recover one or more small seaplanes. The submarine and its plane could then act as a reconnaissance unit ahead of the fleet, an essential role at a time when radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 still did not exist. The first example was the British HMS M2
HMS M2
HMS M2 was a Royal Navy aircraft-carrying submarine shipwrecked in Lyme Bay, Dorset, Britain, on 26 January 1932. She was one of three M-class boats completed.Four M-class submarines replaced the order for the last four K-class, K17-K21...

, followed by the French Surcouf, and numerous aircraft-carrying submarines in the Imperial Japanese Navy
Imperial Japanese Navy submarines
Imperial Japanese Navy submarines originated with the purchase of five Holland type submarines from the United States in 1904. Japanese submarine forces progressively built up strength and expertise, becoming by the beginning of World War II one of the world's most varied and powerful submarine...

.

Germany

Germany had the largest submarine fleet during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. Due to the Treaty of Versailles
Treaty of Versailles
The Treaty of Versailles was one of the peace treaties at the end of World War I. It ended the state of war between Germany and the Allied Powers. It was signed on 28 June 1919, exactly five years after the assassination of Archduke Franz Ferdinand. The other Central Powers on the German side of...

 limiting the surface navy, the rebuilding of the German surface forces had only begun in earnest a year before the outbreak of World War II. Expecting to be able to defeat the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 through underwater warfare, the German High Command pursued commerce raiding
Commerce raiding
Commerce raiding or guerre de course is a form of naval warfare used to destroy or disrupt the logistics of an enemy on the open sea by attacking its merchant shipping, rather than engaging the combatants themselves or enforcing a blockade against them.Commerce raiding was heavily criticised by...

 and immediately stopped all construction on capital surface ships save the nearly completed Bismarck-class battleship
Bismarck class battleship
The Bismarck class was a pair of battleships built by the German Kriegsmarine shortly before the outbreak of World War II. The ships were the largest warships built by the German Navy and the heaviest capital ships ever completed in Europe...

s and two cruisers, switching its resources to submarines, which could be built more quickly. Though it took most of 1940 to expand the production facilities and get the mass production started, more than a thousand submarines were built by the end of the war.

During World War II, Germany utilized submarines to devastating effect in the Second Battle of the Atlantic
Second Battle of the Atlantic
The Battle of the Atlantic was the longest continuous military campaign in World War II, running from 1939 to the defeat of Germany in 1945. At its core was the Allied naval blockade of Germany, announced the day after the declaration of war, and Germany's subsequent counter-blockade. It was at its...

, attempting to cut Britain's supply routes by sinking more merchant ships than Britain could replace. (Shipping was vital to supply Britain's population with food, industry with raw material, and armed forces with fuel and armaments.) While U-boat
U-boat
U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...

s destroyed a significant number of ships, the strategy ultimately failed. Although the U-boats had been updated in the interwar years, the major innovation was improved communications, encrypted using the famous Enigma cipher machine
Enigma machine
An Enigma machine is any of a family of related electro-mechanical rotor cipher machines used for the encryption and decryption of secret messages. Enigma was invented by German engineer Arthur Scherbius at the end of World War I...

. This allowed for mass-attack tactic
Military tactics
Military tactics, the science and art of organizing an army or an air force, are the techniques for using weapons or military units in combination for engaging and defeating an enemy in battle. Changes in philosophy and technology over time have been reflected in changes to military tactics. In...

s (Rudeltaktik, commonly known as "wolfpack"), but was also ultimately the U-boats' downfall.

After putting to sea, U-boats operated mostly on their own, trying to find convoys in areas assigned to them by the High Command. If a convoy was found, the submarine did not attack immediately, but shadowed to guide other submarines in the area. These then attacked more or less simultaneously, preferably at night while surfaced, which offered a speed advantage over the escorting corvette
Corvette
A corvette is a small, maneuverable, lightly armed warship, originally smaller than a frigate and larger than a coastal patrol craft or fast attack craft , although many recent designs resemble frigates in size and role...

s and denied the Allies the ability to use ASDIC, which was unable to detect surfaced submarines.

From September 1939 to the beginning of 1943, the Ubootwaffe ("U-boat force") scored unprecedented success with these tactics, but were too few to have any decisive success. By the spring of 1943, German U-boat construction was at full capacity, but this was more than nullified by increased numbers of convoy escorts and aircraft, as well as technical advances like radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 and sonar. High Frequency Direction Finding (HF/DF, known as Huff-Duff
Huff-Duff
High-frequency direction finding, usually known by its abbreviation HF/DF is the common name for a type of radio direction finding employed especially during the two World Wars....

) and Ultra allowed the Allies to route convoys around wolfpacks when they detected radio transmissions from trailing boats. The results were devastating: from March to July of that year, over 130 U-boats were lost, 41 in May alone. Concurrent Allied losses dropped dramatically, from 750,000 tons in March to only 188,000 in July. Although the Second battle of the Atlantic
Second Battle of the Atlantic
The Battle of the Atlantic was the longest continuous military campaign in World War II, running from 1939 to the defeat of Germany in 1945. At its core was the Allied naval blockade of Germany, announced the day after the declaration of war, and Germany's subsequent counter-blockade. It was at its...

 would continue to the last day of the war, the U-boat arm was unable to stem the tide of personnel and supplies, paving the way for Operation Torch
Operation Torch
Operation Torch was the British-American invasion of French North Africa in World War II during the North African Campaign, started on 8 November 1942....

, Operation Husky, and ultimately, D-Day
D-Day
D-Day is a term often used in military parlance to denote the day on which a combat attack or operation is to be initiated. "D-Day" often represents a variable, designating the day upon which some significant event will occur or has occurred; see Military designation of days and hours for similar...

. Winston Churchill
Winston Churchill
Sir Winston Leonard Spencer-Churchill, was a predominantly Conservative British politician and statesman known for his leadership of the United Kingdom during the Second World War. He is widely regarded as one of the greatest wartime leaders of the century and served as Prime Minister twice...

 wrote the U-boat "peril" was the only thing to ever give him cause to doubt eventual Allied victory.

By the end of the war, almost 3,000 Allied ships (175 warships, 2,825 merchantmen) were sunk by U-boats. Of the 40,000 men in the U-boat service, 28,000 (70%) lost their lives.

Japan

During World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, the IJN
IJN
The abbreviation IJN may refer to:* International Justice Network or IJNetwork, a Human Rights Organization* Imperial Japanese Navy, the navy of Japan from 1868 until it was dissolved in 1947* Institut Jean Nicod, a French interdisciplinary research center...

 operated the most varied fleet of submarines of any navy; including Kaiten
Kaiten
The Kaiten were manned torpedos and suicide craft, they were used by the Imperial Japanese Navy in the final stages of World War II.-History:...

crewed torpedoes, midget submarines (Ko-hyoteki
Ko-hyoteki class submarine
The class was a class of Japanese midget submarines used during World War II. They had hull numbers but no names. For simplicity, they are most often referred to by the hull number of the mother submarine...

 and Kairyu
Kairyu class submarine
The was a class of midget submarines of the Imperial Japanese Navy, designed in 1943–1944, and produced from the beginning of 1945. These submarines were meant to meet the invading American naval forces upon their anticipated approach of Tokyo.-History:...

), medium-range submarines, purpose-built supply submarines and long-range fleet submarines. They also had submarines with the highest submerged speeds during World War II (I-201-class submarines) and submarines that could carry multiple aircraft (I-400-class submarine
I-400 class submarine
The Imperial Japanese Navy submarines were the largest submarines of World War II and remained the largest ever built until the construction of nuclear ballistic missile submarines in the 1960s. They were submarine aircraft carriers able to carry three Aichi M6A Seiran aircraft underwater to their...

). They were also equipped with one of the most advanced torpedoes of the conflict, the oxygen-propelled Type 95
Type 95 torpedo
The Type 95 torpedo was a torpedo of the Imperial Japanese Navy.It was based on the formidable Type 93 torpedo but had a smaller warhead, shorter range and a smaller diameter...

.

Nevertheless, despite their technical prowess, Japan had chosen to utilize its submarines for fleet warfare, and consequently were relatively unsuccessful, as warships were fast, maneuverable and well-defended compared to merchant ships. In 1942, a Japanese submarine sank one aircraft carrier, damaged one battleship, and damaged one destroyer (which sank later) from one torpedo salvo; and during the Battle of Midway
Battle of Midway
The Battle of Midway is widely regarded as the most important naval battle of the Pacific Campaign of World War II. Between 4 and 7 June 1942, approximately one month after the Battle of the Coral Sea and six months after Japan's attack on Pearl Harbor, the United States Navy decisively defeated...

 were able to deliver the coup de grace
Coup de grâce
The expression coup de grâce means a death blow intended to end the suffering of a wounded creature. The phrase can refer to the killing of civilians or soldiers, friends or enemies, with or without the consent of the sufferer...

 to another fleet aircraft carrier, again, sinking another destroyer, for another multiple score from one salvo. But with the lack of fuel oil and air supremacy, Imperial submarines were not able to sustain those kind of results afterwards. By the end of the war, submarines were instead often relegated to transport supplies to island garrisons.

United States

After the attack on Pearl Harbor, many of the U.S. Navy's front-line Pacific Fleet surface ships were destroyed or severely damaged. The submarines survived the attack and carried the war to the enemy. Lacking support vessels, the submarines were asked to independently hunt and destroy Japanese ships and submarines. They did so very effectively and without the assistance of other supporting ships.

During World War II the submarine force was the most effective anti-ship and anti-submarine weapon in the entire American arsenal. Submarines, though only about 2 percent of the U.S. Navy, destroyed over 30 percent of the Japanese Navy, including 8 aircraft carriers, 1 battleship and 11 cruisers. U.S. submarines also destroyed over 60 percent of the Japanese merchant fleet, crippling Japan's ability to supply its military forces and industrial war effort. Allied submarines in the Pacific War
Allied submarines in the Pacific War
Allied submarines were used extensively during the Pacific War and were a key contributor to the defeat of the Empire of Japan. During the war, submarines of the United States Navy were responsible for 55% of Japan's merchant marine losses; other Allied navies added to the toll. The war against...

 destroyed more Japanese shipping, than all other weapons combined. This feat was considerably aided by the Imperial Japanese Navy's failure to provide adequate escort forces for the nation's merchant fleet.

Of note, whereas Japan had the finest submarine torpedoes of the war, the U.S. Navy had the worst: for example, the U.S. Mark 14 torpedo
Mark 14 torpedo
The Mark 14 torpedo was the United States Navy's standard submarine-launched anti-ship torpedo of World War II.This weapon was plagued with many problems which crippled its performance early in the war, and was supplemented by the Mark 18 electric torpedo in the last 2 years of the war...

 typically ran ten feet too deep and was tipped with a Mk VI exploder, with both magnetic influence and contact features, neither reliable. The faulty depth control mechanism of the Mark 14 was corrected in August 1942, but field trials for the exploders were not ordered until mid-1943, when tests in Hawaii and Australia confirmed the flaws. In addition, the Mark 14 sometimes suffered circular runs, which sank at least one U.S. submarine, Tullibee
USS Tullibee (SS-284)
USS Tullibee , a , was the first ship of the United States Navy to be named for the tullibee, a whitefish of central and northern North America. Her keel was laid down on April 1, 1942 at Mare Island, California, by the Mare Island Navy Yard. She was launched on November 11, 1942 sponsored by Mrs....

. Fully operational Mark 14 torpedoes were not put into service until September 1943. The Mark 15 torpedo used by U.S. surface combatants had the same Mk VI exploder and was not fixed until late 1943. One attempt to correct the problems resulted in a wakeless, electric torpedo (the Mark 18
Mark 18 torpedo
The Mark 18 torpedo was an electric torpedo used by the US Navy during World War II.The Mark 18 was built in competition to the Bureau of Ordnance electric torpedoes, which had been in development at the Newport Torpedo Station , Newport, Rhode Island, since the 1920s, in particular the Mark II,...

) being placed in submarine service; Tang
USS Tang (SS-306)
USS Tang was a Balao-class submarine of World War II. She was built and launched in 1943.In her short career, the Tang sank 33 ships displacing 116,454 tons Her commanding officer received the Medal of Honor for her last two engagements...

 was lost to a circular run by one of these torpedoes. Given the prevalence of circular runs, there were probably other losses among boats which simply disappeared.

During World War II, 314 submarines served in the United States Navy, of which nearly 260 were deployed to the Pacific. On December 7, 1941, 111 boats were in commission; 203 submarines from the Gato
Gato class submarine
The United States Navy Gato class submarine formed the core of the submarine service that was largely responsible for the destruction of the Japanese merchant marine and a large portion of the Imperial Japanese Navy in World War II...

, Balao
Balao class submarine
The Balao class was a successful design of United States Navy submarine used during World War II, and with 122 units built, the largest class of submarines in the United States Navy. An improvement on the earlier Gato class, the boats had slight internal differences...

, and Tench
Tench class submarine
Tench-class submarines were a type of submarine built for the United States Navy between 1944 and 1951. They were an evolutionary improvement over the Gato and Balao classes, only about 35 to 40 tons larger, but more strongly built and with a slightly improved internal layout...

 classes were commissioned during the war. During the war, 52 US submarines were lost to all causes, with 48 directly due to hostilities; 3,505 sailors were lost, the highest percentage killed in action
Killed in action
Killed in action is a casualty classification generally used by militaries to describe the deaths of their own forces at the hands of hostile forces. The United States Department of Defense, for example, says that those declared KIA need not have fired their weapons but have been killed due to...

 of any US service arm in World War II. U.S. submarines sank 1,560 enemy vessels, a total tonnage of 5.3 million tons (55% of the total sunk), including 8 aircraft carriers, a battleship, three heavy cruisers, and over 200 other warships. In addition, the Japanese merchant marine
Merchant Navy
The Merchant Navy is the maritime register of the United Kingdom, and describes the seagoing commercial interests of UK-registered ships and their crews. Merchant Navy vessels fly the Red Ensign and are regulated by the Maritime and Coastguard Agency...

 lost 16,200 sailors killed and 53,400 wounded, of some 122,000 at the start of the war, due to submarines.

United Kingdom

The Royal Navy Submarine Service
Royal Navy Submarine Service
The Royal Navy Submarine Service is the submarine element of the Royal Navy. It is sometimes known as the "Silent Service", on account of a submarine being required to operate quietly in order to remain undetected by enemy sonar...

 was primarily used to enforce the classic British blockade
Blockade
A blockade is an effort to cut off food, supplies, war material or communications from a particular area by force, either in part or totally. A blockade should not be confused with an embargo or sanctions, which are legal barriers to trade, and is distinct from a siege in that a blockade is usually...

 role. It therefore chiefly operated in inshore waters and tended to only surface by night.

Its major operating areas were around Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

, the Mediterranean (against the Axis supply routes to North Africa
North Africa
North Africa or Northern Africa is the northernmost region of the African continent, linked by the Sahara to Sub-Saharan Africa. Geopolitically, the United Nations definition of Northern Africa includes eight countries or territories; Algeria, Egypt, Libya, Morocco, South Sudan, Sudan, Tunisia, and...

), and in the Far East. Royal Navy submarines operating out of Trincomalee
Trincomalee
Trincomalee is a port city in Eastern Province, Sri Lanka and lies on the east coast of the island, about 113 miles south of Jaffna. It has a population of approximately 100,000 . The city is built on a peninsula, which divides the inner and outer harbours. Overlooking the Kottiyar Bay,...

 and Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 were a constant threat to Japanese shipping passing through the Malacca Straits.

In the war British submarines sank 2 million tons of enemy shipping and 57 major warships, the latter including 35 submarines. Among these is the only documented instance of a submarine sinking another submarine while both were submerged. This occurred when HMS Venturer
HMS Venturer (P68)
HMS Venturer was a Second World War British submarine.-Construction:Venturer was the lead boat of the British V class submarine, a development of the successful U-class...

 engaged the U864; the Venturer crew manually computed a successful firing solution against a three-dimensionally manoeveuring target using techniques which became the basis of modern torpedo computer targeting systems. Seventy-four British submarines were lost, the majority, 42, in the Mediterranean.

Snorkel

Diesel-electric submarines need air to run their diesel engines, and so carried very large batteries
Battery (electricity)
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...

 for submerged operation. The need to recharge the batteries from the diesel engines limited the endurance of the submarine while submerged and required it to surface regularly for extended periods, during which it was especially vulnerable to detection and attack. The snorkel
Submarine snorkel
A submarine snorkel is a device which allows a submarine to operate submerged while still taking in air from above the surface. Navy personnel often refer to it as the snort.-History:...

, a pre-war Dutch invention, was used to allow German submarines to run their diesel engines whilst running just under the surface, drawing air through a tube from the surface.

The German Navy also experimented with engines that would use hydrogen peroxide
Hydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...

 to allow diesel fuel to be used while submerged, but technical difficulties were great. The Allies experimented with a variety of detection systems, including chemical sensors to "smell
Olfaction
Olfaction is the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertebrates, and, by analogy, sensory cells of the antennae of invertebrates...

" the exhaust of submarines.

Cold-war diesel-electric submarines, such as the Oberon class
Oberon class submarine
The Oberon class was a 27-boat class of British-built diesel-electric submarines based on the successful British Porpoise-class submarine....

, used batteries to power their electric motors in order to run silently. They recharged the batteries using the diesel engines without ever surfacing.

Modern military submarines

The first launch of a cruise missile
Cruise missile
A cruise missile is a guided missile that carries an explosive payload and is propelled, usually by a jet engine, towards a land-based or sea-based target. Cruise missiles are designed to deliver a large warhead over long distances with high accuracy...

 (SSM-N-8 Regulus
SSM-N-8 Regulus
The SSM-N-8A Regulus was a ship and submarine launched, nuclear armed cruise missile deployed by the United States Navy from 1955 to 1964.-Design and development:...

) from a submarine occurred in July 1953 from the deck of USS Tunny, a World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 fleet boat modified to carry this missile with a nuclear warhead
Nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...

. Tunny and her sister boat Barbero were the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

's first nuclear deterrent patrol submarines. They were joined in 1958 by two purpose built Regulus submarines, Grayback
USS Grayback (SSG-574)
USS Grayback , the lead ship of her class of submarine, was the second ship of the United States Navy to be named for the grayback, a small herring of great commercial importance in the Great Lakes....

, Growler
USS Growler (SSG-577)
USS Growler , an early cruise missile submarine of the Grayback class, was the fourth ship of the United States Navy to be named for the growler, a large-mouth black bass.-Construction and training:...

, and, later, by the nuclear powered Halibut
USS Halibut (SSGN-587)
USS Halibut , a unique guided missile submarine turned special operations platform, later redesignated as an attack submarine SSN-587, was the second ship of the United States Navy to be named for the halibut.-Operational history:...

.

In the 1950s, nuclear power
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...

 partially replaced diesel-electric propulsion. Equipment was also developed to extract oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 from sea water. These two innovations gave submarines the ability to remain submerged for weeks or months, and enabled previously impossible voyages such as USS Nautilus
USS Nautilus (SSN-571)
USS Nautilus is the world's first operational nuclear-powered submarine. She was the first vessel to complete a submerged transit beneath the North Pole on August 3, 1958...

' crossing of the North pole
North Pole
The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is, subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets its surface...

 beneath the Arctic ice cap in 1958 and the USS Triton
USS Triton (SSRN-586)
USS Triton , a United States Navy nuclear-powered radar picket submarine, was the first vessel to execute a submerged circumnavigation of the Earth , doing so in early 1960. Triton accomplished this objective during her shakedown cruise while under the command of Captain Edward L. "Ned" Beach, Jr...

s submerged circumnavigation of the world in 1960. Most of the naval submarines built since that time in the United States and the Soviet Union/Russia have been powered by nuclear reactors. The limiting factors in submerged endurance for these vessels are food supply and crew morale in the space-limited submarine.

In 1959–1960, the first ballistic missile submarine
Ballistic missile submarine
A ballistic missile submarine is a submarine equipped to launch ballistic missiles .-Description:Ballistic missile submarines are larger than any other type of submarine, in order to accommodate SLBMs such as the Russian R-29 or the American Trident...

s were put into service by both the United States (George Washington class
George Washington class submarine
The George Washington class was a class of nuclear-powered ballistic missile submarines deployed by the United States Navy. The Navy ordered a class of nuclear-powered submarines armed with long-range strategic missiles on 31 December 1957, and tasked Electric Boat with converting two existing...

) and the Soviet Union (Hotel class
Hotel class submarine
The Hotel class is the general NATO classification for a type of nuclear-powered ballistic missile submarine that was originally put into service by the Soviet Union around 1959. The Soviet designation is Project 658.-Design:...

) as part of the Cold War
Cold War
The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...

 nuclear deterrent strategy.

While the greater endurance and performance from nuclear reactors makes nuclear submarines better for long-distance missions or the protection of a carrier battle group, their reactor cooling pumps have traditionally made them noisier, and thus easier to detect, than conventional diesel-electric submarines. Diesel-electrics have continued to be produced by both nuclear and non-nuclear powers as they lack this limitation, except when required to run the diesel engine to recharge the ship’s battery. Recent technological advances in sound damping, noise isolation, and cancellation have made nuclear subs quieter and substantially eroded this disadvantage. Though far less capable regarding speed and weapons payload, conventional submarines are also cheaper to build. The introduction of air-independent propulsion
Air-independent propulsion
Air-independent propulsion is a term that encompasses technologies which allow a submarine to operate without the need to surface or use a snorkel to access atmospheric oxygen. The term usually excludes the use of nuclear power, and describes augmenting or replacing the diesel-electric propulsion...

 boats, conventional diesel-electric submarines with some kind of auxiliary air-independent electricity generator, have led to increased sales of such types of submarines.

During the Cold War, the United States and the Soviet Union maintained large submarine fleets that engaged in cat-and-mouse games. The Soviet Union suffered the loss of at least four submarines during this period: K-129
Soviet submarine K-129 (Golf II)
K-129 was a Project 629A diesel-electric powered submarine of the Soviet Pacific Fleet, one of six Project 629 strategic ballistic missile submarines attached to the 15th Submarine Squadron based at Rybachiy Naval Base, Kamchatka, commanded by Rear Admiral Rudolf A...

 was lost in 1968 (which the CIA attempted to retrieve from the ocean floor with the Howard Hughes
Howard Hughes
Howard Robard Hughes, Jr. was an American business magnate, investor, aviator, engineer, film producer, director, and philanthropist. He was one of the wealthiest people in the world...

 -designed ship Glomar Explorer), K-8
Soviet submarine K-8
K-8 was a November class submarine of the Soviet Northern Fleet that sank in the Bay of Biscay with its nuclear weapons on board on April 12, 1970...

 in 1970, K-219
Soviet submarine K-219
K-219 was a Navaga-class ballistic missile submarine of the Soviet Navy. She carried 16 SS-N-6 liquid-fuel missiles powered by UDMH with IRFNA, equipped with an estimated 34 nuclear warheads....

 in 1986, and Komsomolets in 1989 (which held a depth record among military submarines—1000 m). Many other Soviet subs, such as K-19
Soviet submarine K-19
K-19, KS-19, BS_19 was one of the first two Soviet submarines of the 658, 658м, 658с class , the first generation nuclear submarine equipped with nuclear ballistic missiles, specifically the R-13 . Its keel was laid down on 17 October 1958, christened on 8 April 1959 and launched on 11 October 1959...

 (the first Soviet nuclear submarine, and the first Soviet sub to reach the North Pole) were badly damaged by fire or radiation leaks. The US lost two nuclear submarines during this time: USS Thresher
USS Thresher (SSN-593)
The second USS Thresher was the lead ship of her class of nuclear-powered attack submarines in the United States Navy. Her loss at sea during deep-diving tests in 1963 is often considered a watershed event in the implementation of the rigorous submarine safety program SUBSAFE.The contract to build...

 due to equipment failure during a test dive while at its operational limit, and USS Scorpion
USS Scorpion (SSN-589)
USS Scorpion was a Skipjack-class nuclear submarine of the United States Navy, and the sixth ship of the U.S. Navy to carry that name. Scorpion was declared lost on 5 June 1968 with 99 crew members dying in the incident. The USS Scorpion is one of two nuclear submarines the U.S...

 due to unknown causes.

During the Indo-Pakistani War of 1971
Indo-Pakistani War of 1971
The Indo-Pakistani War of 1971 was a military conflict between India and Pakistan. Indian, Bangladeshi and international sources consider the beginning of the war to be Operation Chengiz Khan, Pakistan's December 3, 1971 pre-emptive strike on 11 Indian airbases...

, the Pakistan Navy
Pakistan Navy
The Pakistan Navy is the naval warfare/service branch of the Pakistan Armed Forces. Pakistan's Navy is responsible for Pakistan's coastline along the Arabian Sea and the defense of important civilian harbors and military bases...

's Hangor sank the Indian frigate INS Khukri. This was the first kill by a submarine since World War II, and the only one until the United Kingdom employed nuclear-powered submarines against Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

 in 1982 during the Falklands War
Falklands War
The Falklands War , also called the Falklands Conflict or Falklands Crisis, was fought in 1982 between Argentina and the United Kingdom over the disputed Falkland Islands and South Georgia and the South Sandwich Islands...

. The Argentine cruiser General Belgrano
ARA General Belgrano
The ARA General Belgrano was an Argentine Navy light cruiser in service from 1951 until 1982. Formerly the , she saw action in the Pacific theater of World War II before being sold to Argentina. After almost 31 years of service, she was sunk during the Falklands War by the Royal Navy submarine ...

 was sunk by HMS Conqueror
HMS Conqueror (S48)
HMS Conqueror was a nuclear-powered fleet submarine that served in the Royal Navy from 1971 to 1990. She was built by Cammell Laird in Birkenhead...

 (the first sinking by a nuclear-powered submarine in war). The PNS Ghazi
PNS Ghazi
PNS Ghazi was Pakistan Navy 's first ever submarine, leased from United States in 1963. It saw action in the 1965 and 1971 wars between India and Pakistan. The submarine could be armed with up to 28 torpedoes and, in later years, was re-fitted in Turkey for mine-laying capability...

, a Tench-class submarine
Tench class submarine
Tench-class submarines were a type of submarine built for the United States Navy between 1944 and 1951. They were an evolutionary improvement over the Gato and Balao classes, only about 35 to 40 tons larger, but more strongly built and with a slightly improved internal layout...

 on loan to Pakistan from the US, was sunk in the Indo-Pakistani War. It was the first submarine casualty since World War II during war time.

More recently, Russia has had three high profile submarine accidents. The Kursk went down with all hands
Russian submarine Kursk explosion
On 12 August 2000, the Russian Oscar II class submarine Kursk sank in the Barents Sea after an explosion. The investigation showed that a leak of hydrogen peroxide in a torpedo led to explosion of its fuel, causing the submarine to hit the bottom which in turn triggered the detonation of further...

 in 2000; the K-159
Soviet submarine K-159
K-159 was a Project 627A "Kit" nuclear-powered submarine of the Soviet Northern Fleet. Her keel was laid down on 15 August 1962 at the Severodvinsk "Sevmash" Shipyard No. 402...

 sank while being towed to a scrapyard in 2003, with nine lives lost; and the Nerpa had an accident with the fire-extinguishing system resulting in twenty deaths in late 2008.

India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

 launched its first locally built nuclear-powered submarine, the INS Arihant
INS Arihant
INS Arihant is the lead ship of India's Arihant class of nuclear-powered submarines. The 5,000–6,000 tonne vessel was built under the Advanced Technology Vessel project at the Ship Building Centre in Visakhapatnam....

, on July 26, 2009.

A North Korean submarine's torpedo allegedly sank the South Korean navy ship ROKS Cheonan on 26 March 2010.

Polar operations

  • 1903 – Simon Lake
    Simon Lake
    Simon Lake was a Quaker American mechanical engineer and naval architect who obtained over two hundred patents for advances in naval design and competed with John Philip Holland to build the first submarines for the United States Navy.Born in Pleasantville, New Jersey, Lake joined his father's...

     submarine Protector surfaced through ice off Newport, Rhode Island
    Newport, Rhode Island
    Newport is a city on Aquidneck Island in Newport County, Rhode Island, United States, about south of Providence. Known as a New England summer resort and for the famous Newport Mansions, it is the home of Salve Regina University and Naval Station Newport which houses the United States Naval War...

    .
  • 1930 – USS O-12
    USS O-12 (SS-73)
    USS O-12 was an O-class submarine of the United States Navy. Her keel was laid down on 6 March 1916 by the Lake Torpedo Boat Company in Bridgeport, Connecticut....

     operated under ice near Spitsbergen
    Spitsbergen
    Spitsbergen is the largest and only permanently populated island of the Svalbard archipelago in Norway. Constituting the western-most bulk of the archipelago, it borders the Arctic Ocean, the Norwegian Sea and the Greenland Sea...

    .
  • 1937 – Soviet submarine Krasnogvardeyets operated under ice in the Denmark Strait
    Denmark Strait
    The Denmark Strait or Greenland Strait |Sound]]) is an oceanic strait between Greenland and Iceland...

    .
  • 1941–45 – German U-boats operated under ice from the Barents Sea
    Barents Sea
    The Barents Sea is a marginal sea of the Arctic Ocean, located north of Norway and Russia. Known in the Middle Ages as the Murman Sea, the sea takes its current name from the Dutch navigator Willem Barents...

     to the Laptev Sea
    Laptev Sea
    The Laptev Sea is a marginal sea of the Arctic Ocean. It is located between the northern coast of Siberia, the Taimyr Peninsula, Severnaya Zemlya and the New Siberian Islands. Its northern boundary passes from the Arctic Cape to a point with co-ordinates of 79°N and 139°E, and ends at the Anisiy...

    .
  • 1946 – USS Atule
    USS Atule (SS-403)
    USS Atule , a Balao-class submarine, was the only ship of the United States Navy to be named for the atule.Her keel was laid down on 25 November 1943 by the Portsmouth Naval Shipyard in Kittery, Maine. Atule was launched on 6 March 1944 sponsored by Miss Elizabeth Louise Kauffman, the daughter of...

     used upward-beamed fathometer in Operation Nanook in the Davis Strait
    Davis Strait
    Davis Strait is a northern arm of the Labrador Sea. It lies between mid-western Greenland and Nunavut, Canada's Baffin Island. The strait was named for the English explorer John Davis , who explored the area while seeking a Northwest Passage....

    .
  • 1946–47 – USS Sennet
    USS Sennet (SS-408)
    USS Sennet , a Balao-class submarine, was a ship of the United States Navy named for the sennet, a barracuda.Sennet was laid down on 8 March 1944 by the Portsmouth Navy Yard in Kittery, Maine; launched on 6 June 1944, sponsored by Mrs. Roscoe W. Downs; and commissioned on 22 August 1944, Commander...

     used under-ice SONAR
    Sonar
    Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

     in Operation High Jump in the Antarctic.
  • 1947 – USS Boarfish
    USS Boarfish (SS-327)
    USS Boarfish , a Balao-class submarine, was a ship of the United States Navy named for the boarfish, a fish having a projecting hog-like snout....

     used upward-beamed echo sounder under pack ice in the Chukchi Sea
    Chukchi Sea
    Chukchi Sea is a marginal sea of the Arctic Ocean. It is bounded on the west by the De Long Strait, off Wrangel Island, and in the east by Point Barrow, Alaska, beyond which lies the Beaufort Sea. The Bering Strait forms its southernmost limit and connects it to the Bering Sea and the Pacific...

    .
  • 1948 – USS Carp
    USS Carp (SS-338)
    USS Carp , a Balao-class submarine, was the second ship of the United States Navy to be named for the carp, a fresh water fish inhabiting the waters of Europe, Asia, Africa, North and South America....

     developed techniques for making vertical ascents and descents through polynya
    Polynya
    A polynya or polynia is an area of open water surrounded by sea ice. It is now used as geographical term for an area of unfrozen sea within the ice pack. It is a loanword from , , which means a natural ice hole, and was adopted in the 19th century by polar explorers to describe navigable...

    s in the Chukchi Sea.
  • 1952 – USS Redfish
    USS Redfish (SS-395)
    USS Redfish , a Balao-class submarine, was the first ship of the United States Navy to be named for the redfish, a variety of salmon also called blueback, sawqui, red salmon, and nerka. Her keel was laid down on 9 September 1943 by the Portsmouth Navy Yard of Kittery, Maine...

     used an expanded upward-beamed sounder array in the Beaufort Sea
    Beaufort Sea
    The Beaufort Sea is a marginal sea of the Arctic Ocean, located north of the Northwest Territories, the Yukon, and Alaska, west of Canada's Arctic islands. The sea is named after hydrographer Sir Francis Beaufort...

    .
  • 1957 – USS Nautilus
    USS Nautilus (SSN-571)
    USS Nautilus is the world's first operational nuclear-powered submarine. She was the first vessel to complete a submerged transit beneath the North Pole on August 3, 1958...

     reached 87 degrees north near Spitsbergen.
  • 3 August 1958 – Nautilus used an inertial navigation system
    Inertial navigation system
    An inertial navigation system is a navigation aid that uses a computer, motion sensors and rotation sensors to continuously calculate via dead reckoning the position, orientation, and velocity of a moving object without the need for external references...

     to reach the North Pole.
  • 17 March 1959 – USS Skate
    USS Skate (SSN-578)
    USS Skate , the third submarine of the United States Navy named for the skate, a type of ray, was the lead ship of the Skate class of nuclear submarines...

     surfaced through the ice at the north pole.
  • 1960 – USS Sargo
    USS Sargo (SSN-583)
    USS Sargo , a Skate-class nuclear-powered submarine, was the second ship of the United States Navy to be named for the sargo, a food and game fish of the porgy family, inhabiting coastal waters of the southern United States....

     transited 900 miles (1,448.4 km) under ice over the shallow (125 foot deep) Bering-Chukchi shelf.
  • 1960 – USS Seadragon
    USS Seadragon (SSN-584)
    USS Seadragon , a , was the second ship of the United States Navy to be named for the seadragon, a small fish commonly called the dragonet....

     transited the Northwest Passage
    Northwest Passage
    The Northwest Passage is a sea route through the Arctic Ocean, along the northern coast of North America via waterways amidst the Canadian Arctic Archipelago, connecting the Atlantic and Pacific Oceans...

     under ice.
  • 1962 – Soviet November-class submarine
    November class submarine
    The Project 627 class submarine was the Soviet Union's first class of nuclear-powered submarines. The North Atlantic Treaty Organization used the standard radio communication phonetic alphabet to denote submarine classes...

     Leninskiy Komsomol
    Soviet submarine K-3 Leninsky Komsomol
    К-3 was a project 627 "Кит" submarine of the Soviet Navy's Northern Fleet, the first nuclear submarine of the Soviet Union. The vessel was prototyped in wood, with each of five segments scattered between five different locations about Leningrad, including the Astoria Hotel...

     reached the north pole.
  • 1970 – USS Queenfish
    USS Queenfish (SSN-651)
    USS Queenfish , a Sturgeon-class attack submarine, was the second ship of the United States Navy to be named for the queenfish, a small food fish found off the Pacific coast of North America.-Construction and commissioning:...

     carried out an extensive undersea mapping survey of the Siberian continental shelf.
  • 1971 – HMS Dreadnought
    HMS Dreadnought (S101)
    The seventh HMS Dreadnought was the United Kingdom's first nuclear-powered submarine, built by Vickers Armstrongs at Barrow-in-Furness. Launched by Queen Elizabeth II on Trafalgar Day 1960 and commissioned into service with the Royal Navy in April 1963, she continued in service until 1980...

     reached the North Pole.
  • 6 May 1986 – USS Ray
    USS Ray (SSN-653)
    USS Ray , a Sturgeon-class attack submarine, was the second ship of the United States Navy to be named for the rays, various cartilaginous marine fishes characterized by a flat body, large pectoral fins, and a whiplike tail, belonging to the superorder Batoidea, especially the true rays of the...

    , USS Archerfish
    USS Archerfish (SSN-678)
    USS Archerfish , a Sturgeon-class attack submarine, was the second ship of the United States Navy to be named for the archerfish, a family of fish notable for their habit of preying on insects and other animals by shooting them down with squirts of water from the mouth.-Construction and...

     and USS Hawkbill
    USS Hawkbill (SSN-666)
    USS Hawkbill , a Sturgeon-class attack submarine, was the second ship of the United States Navy to be named for the hawksbill, a large sea turtle...

     meet and surface together at the Geographic North Pole. First multi-submarine surfacing at the Pole.
  • 19 May 1987 – HMS Superb
    HMS Superb (S109)
    HMS Superb was a nuclear powered fleet submarine of the Swiftsure class serving in the Royal Navy.She was built by Vickers Shipbuilding Groups, now a division of BAE Systems Submarine Solutions. HMS Superb was launched on 30 November 1974 at Barrow-in-Furness, Cumbria and commissioned into the...

     joined USS Billfish
    USS Billfish (SSN-676)
    USS Billfish , a Sturgeon-class attack submarine, was the second ship of the United States Navy to be named for the billfish, a name used for any fish, such as gar or spearfish, with bill-shaped jaws.-Construction and commissioning:...

     and USS Sea Devil
    USS Sea Devil (SSN-664)
    USS Sea Devil , a Sturgeon-class attack submarine, was the second ship of the United States Navy to be named for the sea devil , also known as the manta ray or devil ray, the largest of all living rays, noted for power and endurance.-Construction and commissioning:The contract to build Sea Devil...

     at the North Pole. The first time British and Americans met at the North Pole.
  • March 2007 – USS Alexandria
    USS Alexandria (SSN-757)
    USS Alexandria , a Los Angeles-class nuclear-powered attack submarine, is the third ship of the United States Navy to be named for both Alexandria, Virginia, and Alexandria, Louisiana.- Construction :...

     participated in the Joint U.S. Navy/Royal Navy
    Royal Navy
    The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

     Ice Exercise 2007 (ICEX-2007) in the Arctic Ocean with the Trafalgar-class submarine
    Trafalgar class submarine
    The Trafalgar class is a class of nuclear-powered fleet submarines in service with the Royal Navy. They are a direct follow on from the Swiftsure class and were, until the introduction of the Astute class, the Royal Navy's most advanced nuclear fleet submarines.Seven boats were built and...

     HMS Tireless
    HMS Tireless (S88)
    HMS Tireless is a nuclear submarine of the Royal Navy and is the third vessel of her class. She is the second submarine of the Royal Navy to bear this name...

    .
  • March 2009 – USS Annapolis
    USS Annapolis (SSN-760)
    USS Annapolis , is the tenth "improved" Los Angeles-class submarine, and is sister-ship to the USS Springfield . Homeported in Groton, CT, she is assigned to Submarine Development Squadron 12...

     took part in Ice Exercise 2009
    Ice Exercise 2009
    Ice Exercise 2009 ' was a two-week US naval military exercise that took place in March 2009. Its aim was to test submarine operability and war-fighting capability in Arctic conditions...

     to test submarine operability and war-fighting capability in Arctic conditions.

Military usage

Before and during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, the primary role of the submarine was anti-surface ship warfare. Submarines would attack either on the surface or submerged, using torpedo
Torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

es or (on the surface) deck guns. They were particularly effective in sinking Allied transatlantic shipping in both World Wars, and in disrupting Japanese supply routes and naval operations in the Pacific in World War II.

Mine
Naval mine
A naval mine is a self-contained explosive device placed in water to destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, an enemy vessel...

-laying submarines were developed in the early part of the 20th century. The facility was used in both World Wars. Submarines were also used for inserting and removing covert agents and military forces, for intelligence gathering, and to rescue aircrew during air attacks on islands, where the airmen would be told of safe places to crash-land so the submarines could rescue them. Submarines could carry cargo through hostile waters or act as supply vessels for other submarines.

Submarines could usually locate and attack other submarines only on the surface, although managed to sink U-864 with a four torpedo spread while both were submerged. The British developed a specialized anti-submarine submarine in WWI, the R class
British R class submarine
The R-class submarines were a class of 12 small British diesel-electric submarines built for the Royal Navy during World War I, and were forerunners of the modern hunter-killer submarines, in that they were designed specifically to attack and sink enemy submarines, their battery capacity and hull...

. After WWII, with the development of the homing torpedo, better sonar
Sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

 systems, and nuclear propulsion
Nuclear navy
Nuclear navy, or nuclear powered navy consists of ships powered by relatively small onboard nuclear reactors known as naval reactors. The concept was revolutionary for naval warfare when first proposed, as it meant that these vessels did not need to stop for fuel like their conventional...

, submarines also became able to hunt each other effectively.

The development of submarine-launched ballistic missile
Submarine-launched ballistic missile
A submarine-launched ballistic missile is a ballistic missile capable of delivering a nuclear warhead that can be launched from submarines. Modern variants usually deliver multiple independently targetable reentry vehicles each of which carries a warhead and allows a single launched missile to...

 and submarine-launched cruise missiles gave submarines a substantial and long-ranged ability to attack both land and sea targets with a variety of weapons ranging from cluster bomb
Cluster bomb
A cluster munition is a form of air-dropped or ground-launched explosive weapon that releases or ejects smaller sub-munitions. Commonly, this is a cluster bomb that ejects explosive bomblets that are designed to kill enemy personnel and destroy vehicles...

s to nuclear weapon
Nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...

s.

The primary defense of a submarine lies in its ability to remain concealed in the depths of the ocean. Early submarines could be detected by the sound they made. Water is an excellent conductor of sound (much better than air), and submarines can detect and track comparatively noisy surface ships from long distances. Modern submarines are built with an emphasis on stealth. Advanced propeller designs, extensive sound-reducing insulation, and special machinery allow a submarine to be as quiet as ambient ocean noise, making them difficult to detect. It takes specialized technology to find and attack modern submarines.

Active sonar uses the reflection of sound emitted from the search equipment to detect submarines. It has been used since WWII by surface ships, submarines and aircraft (via dropped buoys and helicopter "dipping" arrays), but it gives away the position of the emitter and is susceptible to counter-measures.

A concealed military submarine is a real threat, and because of its stealth, can force an enemy navy to waste resources searching large areas of ocean and protecting ships against attack. This advantage was vividly demonstrated in the 1982 Falklands War
Falklands War
The Falklands War , also called the Falklands Conflict or Falklands Crisis, was fought in 1982 between Argentina and the United Kingdom over the disputed Falkland Islands and South Georgia and the South Sandwich Islands...

 when the British nuclear-powered submarine HMS Conqueror
HMS Conqueror (S48)
HMS Conqueror was a nuclear-powered fleet submarine that served in the Royal Navy from 1971 to 1990. She was built by Cammell Laird in Birkenhead...

 sank the Argentine cruiser General Belgrano
ARA General Belgrano
The ARA General Belgrano was an Argentine Navy light cruiser in service from 1951 until 1982. Formerly the , she saw action in the Pacific theater of World War II before being sold to Argentina. After almost 31 years of service, she was sunk during the Falklands War by the Royal Navy submarine ...

. After the sinking the Argentine Navy recognised that they had no effective defense against submarine attack, and the Argentine surface fleet withdrew to port for the remainder of the war, though an Argentine submarine remained at sea.

Civil usage

Although the majority of the world's submarines are military, there are some civil submarines. They have a variety of uses, including tourism, exploration, oil and gas platform inspections and pipeline surveys. The first tourist submarine was launched in 1985, and by 1997 there were 45 of them operating around the world.
Submarines with a crush depth in the range of 400–500 ft (121.9–152.4 ) are operated in several areas worldwide, typically with bottom depths around 100 to 120 ft (30.5 to 36.6 ), with a carrying capacity of 50 to 100 passengers. In a typical operation (for example, Atlantis submarines
Atlantis submarines
Atlantis submarines is a passenger submarine company. The company currently has 12 submarines and operates undersea tours in Grand Cayman, Barbados, Aruba, Guam, St...

), a surface vessel carries passengers to an offshore operating area, where passengers are exchanged with those of the submarine. The submarine then visits underwater points of interests, typically either natural or artificial reef structures. To surface safely without danger of collision the location of the submarine is marked with an air release and movement to the surface is coordinated by an observer in a support craft.
A recent development is the deployment of so called narco submarine
Narco submarine
A narco-submarine is a type of custom-made ocean-going self-propelled submersible vessel built by drug traffickers to smuggle drugs. They are especially known to be used by Colombian drug cartel members to export cocaine from Colombia to Mexico, which is often then transported overland to the...

s by South American drug smugglers, in order to evade detection. Although they occasionally deploy true submarines, most are self-propelled semi-submersibles, where a portion of the craft remains above water at all times.
On September 2011, Colombian authority have seized 16-meter long submersible and could hold a crew of 5 with cost about $2 million. The vessel was belonging to FARC rebels and had the capacity to carry at least 7 tonnes of drugs.

Submersion and trimming

All surface ships, as well as surfaced submarines, are in a positively buoyant
Buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...

 condition, weighing less than the volume of water they would displace if fully submerged. To submerge hydrostatically, a ship must have negative buoyancy, either by increasing its own weight or decreasing its displacement of water. To control their weight, submarines have ballast tanks, which can be filled with outside water or pressurized air.

For general submersion or surfacing, submarines use the forward and aft tanks, called Main Ballast Tanks or MBTs, which are filled with water to submerge, or filled with air to surface. Under submerged conditions, MBTs generally remain flooded, which simplifies their design, and on many submarines these tanks are a section of interhull space. For more precise and quick control of depth, submarines use smaller Depth Control Tanks or DCTs, also called hard tanks due to their ability to withstand higher pressure. The amount of water in depth control tanks can be controlled either to reflect changes in outside conditions or change depth. Depth control tanks can be located either near the submarine's center of gravity
Center of gravity
In physics, a center of gravity of a material body is a point that may be used for a summary description of gravitational interactions. In a uniform gravitational field, the center of mass serves as the center of gravity...

, or separated along the submarine body to prevent affecting trim
Dynamic trimming
Dynamic trimming is a method of operating seagoing vessels in a way that ensures minimum water resistance in all circumstances. The method is based on collection and multidimensional analysis of exact real-time data on vessel attitude....

.

When submerged, the water pressure on submarine's hull can reach 4 MPa (580.2 psi) for steel submarines and up to 10 MPa (1,450.4 psi) for titanium submarines like Komsomolets
Soviet submarine K-278 Komsomolets
K-278 Komsomolets was the only Project 685 Плавник nuclear-powered attack submarine of the Soviet Navy. The boat sank in 1989 and is currently resting on the floor of the Barents Sea, one mile deep, with its nuclear reactor and two nuclear warheads still on board...

, while interior pressure remains relatively unchanged. This difference results in hull compression, which decreases displacement. Water density also increases with depth, as the salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...

 and pressure are higher, but this incompletely compensates for hull compression, so buoyancy decreases as depth increases. A submerged submarine is in an unstable equilibrium, having a tendency to either fall or float to the surface. Keeping a constant depth requires continual operation of either the depth control tanks or control surfaces.

Submarines in a neutral buoyancy condition are not intrinsically trim-stable. To maintain desired trim, submarines use forward and aft trim tanks. Pumps can move water between these, changing weight distribution, creating a moment pointing the sub up or down. A similar system is sometimes used to maintain stability.

The hydrostatic effect of variable ballast tanks is not the only way to control the submarine underwater. Hydrodynamic maneuvering is done by several surfaces, which can be moved to create hydrodynamic forces when a submarine moves at sufficient speed. The stern planes, located near the propeller and normally horizontal, serve the same purpose as the trim tanks, controlling the trim, and are commonly used, while other control surfaces may not be present on many submarines. The fairwater planes on the sail and/or bow planes on the main body, both also horizontal, are closer to the centre of gravity, and are used to control depth with less effect on the trim.

When a submarine performs an emergency surfacing, all depth and trim methods are used simultaneously, together with propelling the boat upwards. Such surfacing is very quick, so the sub may even partially jump out of the water, potentially damaging submarine systems.

Overview

Modern submarines are cigar-shaped. This design, visible in early submarines (see below) is sometimes called a "teardrop hull
Teardrop hull
A teardrop hull is a submarine hull design which emphasizes hydrodynamic flow above all other factors. Benefits over previous types include increased underwater speed and a smaller acoustic signature, making detection by sonar more difficult...

". It reduces the hydrodynamic drag
Drag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...

 when submerged, but decreases the sea-keeping capabilities and increases drag while surfaced. Since the limitations of the propulsion systems of early submarines forced them to operate surfaced most of the time, their hull designs were a compromise. Because of the slow submerged speeds of those subs, usually well below 10 kt (18 km/h), the increased drag for underwater travel was acceptable. Late in World War II, when technology allowed faster and longer submerged operation and increased aircraft surveillance forced submarines to stay submerged, hull designs became teardrop shaped again to reduce drag and noise. On modern military submarines the outer hull is covered with a layer of sound-absorbing rubber, or anechoic plating
Anechoic tile
Anechoic tiles are rubber or synthetic polymer tiles containing thousands of tiny voids, applied to the outer hulls of military ships and submarines, as well as anechoic chambers...

, to reduce detection.

The occupied pressure hulls of deep diving submarines such as DSV Alvin
DSV Alvin
Alvin is a manned deep-ocean research submersible owned by the United States Navy and operated by the Woods Hole Oceanographic Institution in Woods Hole, Massachusetts. The vehicle was built by General Mills' Electronics Group in the same factory used to manufacture breakfast cereal-producing...

 are spherical instead of cylindrical. This allows a more even distribution of stress at the great depth. A titanium frame is usually affixed to the pressure hull, providing attachment for ballast and trim systems, scientific instrumentation, battery packs, syntactic flotation foam
Syntactic foam
Syntactic foams are composite materials synthesized by filling a metal, polymer or ceramic matrix with hollow particles called microballoons, "syntactic" meaning "put together"...

, and lighting.

A raised tower on top of a submarine accommodates the periscope
Periscope
A periscope is an instrument for observation from a concealed position. In its simplest form it consists of a tube with mirrors at each end set parallel to each other at a 45-degree angle....

 and electronics masts, which can include radio, radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

, electronic warfare
Electronic warfare
Electronic warfare refers to any action involving the use of the electromagnetic spectrum or directed energy to control the spectrum, attack an enemy, or impede enemy assaults via the spectrum. The purpose of electronic warfare is to deny the opponent the advantage of, and ensure friendly...

, and other systems including the snorkel mast. In many early classes of submarines (see history), the control room, or "conn", was located inside this tower, which was known as the "conning tower
Conning tower
A conning tower is a raised platform on a ship or submarine, often armored, from which an officer can con the vessel; i.e., give directions to the helmsman. It is usually located as high on the ship as practical, to give the conning team good visibility....

". Since then, the conn has been located within the hull of the submarine, and the tower is now called the "sail". The conn is distinct from the "bridge", a small open platform in the top of the sail, used for observation during surface operation.

"Bathtubs" are related to conning towers but are used on smaller submarines. The bathtub is a metal cylinder surrounding the hatch that prevents waves from breaking directly into the cabin. It is needed because surfaced submarines have limited freeboard
Freeboard (nautical)
In sailing and boating, freeboardmeans the distance from the waterline to the upper deck level, measured at the lowest point of sheer where water can enter the boat or ship...

, that is, they lie low in the water. Bathtubs help prevent swamping the vessel.


Single/double hull

Modern submarines and submersibles, as well as the oldest ones, usually have a single hull. Large submarines generally have an additional hull or hull sections outside. This external hull, which actually forms the shape of submarine, is called the outer hull (casing in the Royal Navy) or light hull, as it does not have to withstand a pressure difference. Inside the outer hull there is a strong hull, or pressure hull, which withstands sea pressure and has normal atmospheric pressure inside.

As early as World War I, it was realized that the optimal shape for withstanding pressure conflicted with the optimal shape for seakeeping and minimal drag, and construction difficulties further complicated the problem. This was solved either by a compromise shape, or by using two hulls; internal for holding pressure, and external for optimal shape. Until the end of World War II, most submarines had an additional partial cover on the top, bow and stern, built of thinner metal, which was flooded when submerged. Germany went further with the Type XXI, a general predecessor of modern submarines, in which the pressure hull was fully enclosed inside the light hull, but optimized for submerged navigation, unlike earlier designs that were optimized for surface operation.
After World War II, approaches split. The Soviet Union changed its designs, basing them on German developments. All post–World War II heavy Soviet and Russian submarines are built with a double hull
Double hull
A double hull is a ship hull design and construction method invented by Leonardo da Vinci where the bottom and sides of the ship have two complete layers of watertight hull surface: one outer layer forming the normal hull of the ship, and a second inner hull which is some distance inboard,...

 structure. American and most other Western submarines switched to a primarily single-hull approach. They still have light hull sections in the bow and stern, which house main ballast tanks and provide a hydrodynamically optimized shape, but the main cylindrical hull section has only a single plating layer. The double hulls are being considered for future submarines in the United States to improve payload capacity, stealth and range.

Pressure hull

The pressure hull is generally constructed of thick high strength steel with a complex structure and high strength reserve, and is separated with watertight bulkheads
Bulkhead (partition)
A bulkhead is an upright wall within the hull of a ship or within the fuselage of an airplane. Other kinds of partition elements within a ship are decks and deckheads.-Etymology:...

 into several compartments
Compartmentalization (fire protection)
Compartmentalization in structures, such as land-based buildings, traffic tunnels, ships, aerospace vehicles, or submarines, is the fundamental basis and aim of passive fire protection....

. There are also examples of more than two hulls in a submarine, like the Typhoon class
Typhoon class submarine
The Project 941 or Akula, Russian "Акула" class submarine is a type of nuclear-powered ballistic missile submarine deployed by the Soviet Navy in the 1980s...

, which has two main pressure hulls and three smaller ones for control room, torpedoes and steering gear, with the missile launch system between the main hulls.

The dive depth
Submarine depth ratings
Depth ratings are primary design parameters and measures of a submarine's ability to operate underwater. The depths to which submarines can dive are limited by the strengths of their hulls...

 cannot be increased easily. Simply making the hull thicker increases the weight and requires reduction of onboard equipment weight, ultimately resulting in a bathyscaphe
Bathyscaphe
A bathyscaphe is a free-diving self-propelled deep-sea submersible, consisting of a crew cabin similar to a bathysphere, but suspended below a float rather than from a surface cable, as in the classic bathysphere design....

. This is acceptable for civilian research submersibles, but not military submarines.

WWI submarines had hulls of carbon steel, with a 100 metres (328.1 ft) maximum depth. During WWII, high-strength alloyed steel
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...

 was introduced, allowing 200 metres (656.2 ft) depths. High-strength alloy steel remains the primary material for submarines today, with 250–400 m (820.2–1,312.3 ft) depths, which cannot be exceeded on a military submarine without design compromises. To exceed that limit, a few submarines were built with titanium
Titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....

 hulls. Titanium can be stronger than steel, lighter, and is not ferromagnetic
Ferromagnetism
Ferromagnetism is the basic mechanism by which certain materials form permanent magnets, or are attracted to magnets. In physics, several different types of magnetism are distinguished...

, important for stealth. Titanium submarines were built by the Soviet Union, which developed specialized high-strength alloys. It has produced several types of titanium submarines. Titanium alloys allow a major increase in depth, but other systems need to be redesigned to cope, so test depth was limited to 1000 metres (3,280.8 ft) for the Soviet submarine Komsomolets
Soviet submarine K-278 Komsomolets
K-278 Komsomolets was the only Project 685 Плавник nuclear-powered attack submarine of the Soviet Navy. The boat sank in 1989 and is currently resting on the floor of the Barents Sea, one mile deep, with its nuclear reactor and two nuclear warheads still on board...

, the deepest-diving combat submarine. An Alfa-class submarine
Alfa class submarine
The Soviet Union/Russian Navy Project 705 was a class of hunter/killer nuclear powered submarines. The class is also known by the NATO reporting name of Alfa...

 may have successfully operated at 1300 metres (4,265.1 ft), though continuous operation at such depths would produce excessive stress on many submarine systems. Titanium does not flex as readily as steel, and may become brittle during many dive cycles. Despite its benefits, the high cost of titanium construction led to the abandonment of titanium submarine construction as the Cold War ended. Deep diving civilian submarines have used thick acrylic pressure hulls.

The deepest Deep Submergence Vehicle
Deep Submergence Vehicle
A Deep Sea Submergence Vehicle is a deep diving manned submarine that is self-propelled. The term DSV is generally one used by the United States Navy, though several navies operate vehicles that can be accurately described as DSVs...

 (DSV) to date is Trieste
Bathyscaphe Trieste
The Trieste is a Swiss-designed, Italian-built deep-diving research bathyscaphe with a crew of two, which reached a record maximum depth of about , in the deepest known part of the Earth's oceans, the Challenger Deep, in the Mariana Trench near Guam, on January 23, 1960, crewed by Jacques Piccard ...

. On October 5, 1959 Trieste departed San Diego for Guam
Guam
Guam is an organized, unincorporated territory of the United States located in the western Pacific Ocean. It is one of five U.S. territories with an established civilian government. Guam is listed as one of 16 Non-Self-Governing Territories by the Special Committee on Decolonization of the United...

 aboard the freighter Santa Maria to participate in Project Nekton
Project Nekton
Project Nekton was the codename for a series of shallow test dives and deep-submergence operations in the Pacific Ocean near Guam that saw the United States Navy-owned research bathyscaphe Trieste enter the Challenger Deep, the deepest surveyed point in the world's oceans.The series of dives began...

, a series of very deep dives in the Mariana Trench
Mariana Trench
The Mariana Trench or Marianas Trench is the deepest part of the world's oceans. It is located in the western Pacific Ocean, to the east of the Mariana Islands. The trench is about long but has a mean width of only...

. On January 23, 1960, Trieste reached the ocean floor in the Challenger Deep (the deepest southern part of the Mariana Trench), carrying Jacques Piccard
Jacques Piccard
Jacques Piccard was a Swiss oceanographer and engineer, known for having developed underwater vehicles for studying ocean currents. He was one of only two people, along with Lt...

 (son of Auguste) and Lieutenant Don Walsh
Don Walsh
Don Walsh is an American oceanographer, explorer and marine policy specialist. He and Jacques Piccard were aboard the bathyscaphe Trieste when it made a record maximum descent into the Mariana Trench on 23 January 1960, the deepest point of the world's ocean...

, USN. This was the first time a vessel, manned or unmanned, had reached the deepest point in the Earth's oceans. The onboard systems indicated a depth of 11521 metres (37,799 ft), although this was later revised to 10916 metres (35,814 ft) and more accurate measurements made in 1995 have found the Challenger Deep to be slightly shallower, at 10911 metres (35,797 ft).

Building a pressure hull is difficult, as it must withstand pressures at its required diving depth. When the hull is perfectly round in cross-section, the pressure is evenly distributed, and causes only hull compression. If the shape is not perfect, the hull is bent, with several points heavily strained. Inevitable minor deviations are resisted by stiffener rings, but even a one inch (25 mm) deviation from roundness results in over 30 percent decrease of maximal hydrostatic load and consequently dive depth. The hull must therefore be constructed with high precision. All hull parts must be welded without defects, and all joints are checked multiple times with different methods, contributing to the high cost of modern submarines. (For example, each Virginia-class attack submarine
Virginia class submarine
The Virginia class is a class of nuclear-powered fast attack submarines in service with the United States Navy. The submarines are designed for a broad spectrum of open-ocean and littoral missions...

 costs US$2.6 billion
1000000000 (number)
1,000,000,000 is the natural number following 999,999,999 and preceding 1,000,000,001.In scientific notation, it is written as 109....

, over US$200,000 per ton
Long ton
Long ton is the name for the unit called the "ton" in the avoirdupois or Imperial system of measurements, as used in the United Kingdom and several other Commonwealth countries. It has been mostly replaced by the tonne, and in the United States by the short ton...

 of displacement.)

Propulsion

Originally, submarines were human propelled. The first mechanically driven submarine was the 1863 French Plongeur, which used compressed air for propulsion. Anaerobic propulsion was first employed by the Spanish Ictineo II in 1864, which used a solution of zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

, manganese dioxide, and potassium chlorate
Potassium chlorate
Potassium chlorate is a compound containing potassium, chlorine and oxygen atoms, with the molecular formula KClO3. In its pure form, it is a white crystalline substance. It is the most common chlorate in industrial use...

 to generate sufficient heat to power a steam engine, while also providing oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 for the crew. A similar system was not employed again until 1940 when the German Navy tested a hydrogen peroxide
Hydrogen peroxide
Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...

-based system, the Walter
Hellmuth Walter
Hellmuth Walter was a German engineer who pioneered research into rocket engines and gas turbines...

 turbine
Turbine
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...

, on the experimental V-80 submarine and later on the naval U-791 and type XVII submarines.

Until the advent of nuclear marine propulsion
Nuclear marine propulsion
Nuclear marine propulsion is propulsion of a ship by a nuclear reactor. Naval nuclear propulsion is propulsion that specifically refers to naval warships...

, most 20th century submarines used batteries for running underwater and gasoline
Gasoline
Gasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...

 (petrol) or diesel
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...

 engines on the surface, and for battery recharging. Early submarines used gasoline, but this quickly gave way to kerosene (paraffin)
Kerosene
Kerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin or paraffin oil in the United Kingdom, Hong Kong, Ireland and South Africa, is a combustible hydrocarbon liquid. The name is derived from Greek keros...

, then diesel, because of reduced flammability. Diesel-electric became the standard means of propulsion. The diesel or gasoline engine and the electric motor, separated by clutches, were initially on the same shaft driving the propeller. This allowed the engine to drive the electric motor as a generator to recharge the batteries and also propel the submarine. The clutch between the motor and the engine would be disengaged when the submarine dived, so that the motor could drive the propeller. The motor could have multiple armatures on the shaft, which could be electrically coupled in series for slow speed and in parallel for high speed. (These connections were called "group down" and "group up", respectively.)
Diesel-electric

Early submarines used a direct mechanical connection between the engine and propeller, switching between diesel engines for surface running, and electric motors for submerged propulsion.

In 1928 the United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

's Bureau of Engineering proposed a diesel-electric transmission; instead of driving the propeller directly while running on the surface, the submarine's diesel would drive a generator which could either charge the submarine's batteries or drive the electric motor. This meant that motor speed was independent of the diesel engine's speed, and the diesel could run at an optimum and non-critical speed, while one or more of the diesel engines could be shut down for maintenance while the submarine continued to run using battery power. The concept was pioneered in 1929 in the S-class submarines
United States S class submarine
The United States' S-class submarines, often simply called S-boats , were the first class of submarines built to a United States Navy design....

 S-3
USS S-3 (SS-107)
USS S-3 was the prototype of the "Government-type" S-class submarines of the United States Navy. Her keel was laid down on 29 August 1917 by the Portsmouth Navy Yard. She was launched on 21 December 1918 sponsored by Mrs. William L. Hill, and commissioned on 30 January 1919 with Commander John W...

, S-6
USS S-6 (SS-111)
USS S-6 was a second-group S-class submarine of the United States Navy. Her keel was laid down on 29 January 1918 by the Portsmouth Navy Yard. She was launched on 23 December 1919 sponsored by Ms. Eleanor Westcott; and commissioned on 17 May 1920 with Lieutenant Commander George B...

, and S-7
USS S-7 (SS-112)
USS S-7 was a second-group S-class submarine of the United States Navy. Her keel was laid down on 29 January 1918 by the Portsmouth Navy Yard. She was launched on 5 February 1920 sponsored by Mrs. Henry L...

 to test the concept. No other navy adopted the system before 1945, apart from the Royal Navy's U-class submarines
British U class submarine
The British U class submarines were a class of 49 small submarines built just before and during the Second World War...

, though some submarines of the Imperial Japanese Navy used separate diesel generators for low speed running.

Other advantages of such an arrangement were that a submarine could travel slowly with the engines at full power to recharge the batteries quickly, reducing time on the surface or on snorkel
Submarine snorkel
A submarine snorkel is a device which allows a submarine to operate submerged while still taking in air from above the surface. Navy personnel often refer to it as the snort.-History:...

. It was then possible to insulate
Soundproofing
Soundproofing is any means of reducing the sound pressure with respect to a specified sound source and receptor. There are several basic approaches to reducing sound: increasing the distance between source and receiver, using noise barriers to reflect or absorb the energy of the sound waves, using...

 the noisy diesel engines from the pressure hull, making the submarine quieter. Additionally, diesel-electric transmissions were more compact.

Air-independent propulsion

During the Second World War, German Type XXI submarine
German Type XXI submarine
Type XXI U-boats, also known as "Elektroboote", were the first submarines designed to operate primarily submerged, rather than as surface ships that could submerge as a means to escape detection or launch an attack.-Description:...

s were designed to carry hydrogen peroxide for long-term, fast air-independent propulsion, but were ultimately built with very large batteries instead. At the end of the War, the British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 and Russians experimented with hydrogen peroxide/kerosene (paraffin) engines which could be used surfaced and submerged. The results were not encouraging; although the Russians deployed a class of submarines with this engine type (codenamed Quebec
Quebec class submarine
The Quebec-class submarine was the NATO reporting name of the Soviet Project 615 submarine class, a small coastal attack submarine of the late 1950s.-Background:...

 by NATO), they were considered unsuccessful.

Today several navies use air-independent propulsion. Notably Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 uses Stirling technology
Stirling engine
A Stirling engine is a heat engine operating by cyclic compression and expansion of air or other gas, the working fluid, at different temperature levels such that there is a net conversion of heat energy to mechanical work....

 on the Gotland-class
Gotland class submarine
In 2004, the Swedish government received a request from the United States of America to lease HMS Gotland – Swedish-flagged, commanded and manned, for a duration of one year for use in anti-submarine warfare exercises. The Swedish government granted this request in October 2004, with both...

 and Södermanland-class
Södermanland class submarine
The Swedish Södermanland class of diesel-electric submarines consist of the HMS Södermanland and HMS Östergötland. These two submarines were originally launched as Västergötland class submarines in 1987 and 1990, and have been relaunched as a new class after extensive modernization 2003 and 2004 by...

 submarines. The Stirling engine is heated by burning diesel fuel with liquid oxygen
Liquid oxygen
Liquid oxygen — abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries — is one of the physical forms of elemental oxygen.-Physical properties:...

 from cryogenic tanks. A newer development in air-independent propulsion is hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 fuel cells, first used on the German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 Type 212 submarine
Type 212 submarine
The German Type 212 class, also Italian Todaro class, is a highly advanced design of non-nuclear submarine developed by Howaldtswerke-Deutsche Werft AG and Fincantieri S.p.a. for the German and Italian Navy. It features diesel propulsion and an additional air-independent propulsion system using...

, with nine 34 kW or two 120 kW cells and soon to be used in the new Spanish
Spanish Navy
The Spanish Navy is the maritime branch of the Spanish Armed Forces, one of the oldest active naval forces in the world. The Armada is responsible for notable achievements in world history such as the discovery of Americas, the first world circumnavigation, and the discovery of a maritime path...

 S-80 class
S-80 class
The S-80 Class is a series of submarines of advanced technology that is currently under construction for the Spanish Navy. Initially there will be four units, with a future expansion to six, two of which are in production by the Spanish company Navantia at its factory in Cartagena...

 submarines.

Nuclear power

Steam power was resurrected in the 1950s with a nuclear-powered steam turbine driving a generator. By eliminating the need for atmospheric oxygen, the length of time that a modern submarine could remain submerged was limited only by its food stores, as breathing air was recycled and fresh water distilled
Distillation
Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....

 from seawater. Nuclear-powered submarines have a relatively small battery and diesel engine/generator powerplant for emergency use if the reactors must be shut down.

Nuclear power is now used in all large submarines, but due to the high cost and large size of nuclear reactors, smaller submarines still use diesel-electric propulsion. The ratio of larger to smaller submarines depends on strategic needs. The US Navy, French Navy
French Navy
The French Navy, officially the Marine nationale and often called La Royale is the maritime arm of the French military. It includes a full range of fighting vessels, from patrol boats to a nuclear powered aircraft carrier and 10 nuclear-powered submarines, four of which are capable of launching...

, and the British Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 operate only nuclear submarines, which is explained by the need for distant operations. Other major operators rely on a mix of nuclear submarines for strategic purposes and diesel-electric submarines for defence. Most fleets have no nuclear submarines, due to the limited availability of nuclear power and submarine technology.

Diesel-electric submarines have a stealth advantage over their nuclear counterparts. Nuclear submarines generate noise from coolant pumps and turbo-machinery needed to operate the reactor, even at low power levels. Some nuclear submarines such as the American Ohio class
Ohio class submarine
The Ohio class is a class of nuclear-powered submarines used by the United States Navy. The United States has 18 Ohio-class submarines:...

 can operate with their reactor coolant pumps secured, making them quieter than electric subs. A conventional submarine operating on batteries is almost completely silent, the only noise coming from the shaft bearings, propeller, and flow noise around the hull, all of which stops when the sub hovers in mid water to listen, leaving only the noise from crew activity. Commercial submarines usually rely only on batteries, since they never operate independently of a mother ship.

Several serious nuclear and radiation accidents
Nuclear and radiation accidents by death toll
There have been more than 20 nuclear and radiation accidents involving fatalities. These involved nuclear power plant accidents, nuclear submarine accidents, radiotherapy accidents, and other mishaps.-Chernobyl disaster:...

 have involved nuclear submarine mishaps. The Soviet submarine K-19
Soviet submarine K-19
K-19, KS-19, BS_19 was one of the first two Soviet submarines of the 658, 658м, 658с class , the first generation nuclear submarine equipped with nuclear ballistic missiles, specifically the R-13 . Its keel was laid down on 17 October 1958, christened on 8 April 1959 and launched on 11 October 1959...

 reactor accident in 1961 resulted in 8 deaths and more than 30 other people were over-exposed to radiation. The Soviet submarine K-27
Soviet submarine K-27
The K-27 was the only submarine of Projekt 645 in the Soviet Navy. Project 645 did not have or need its own NATO reporting name. That project produced just one test model nuclear submarine, one which incorporated a pair of experimental VT-1 nuclear reactors that used a liquid-metal coolant ,...

 reactor accident in 1968 resulted in 9 fatalities and 83 other injuries. The Soviet submarine K-431
Soviet submarine K-431
The Soviet submarine K-431 was a Soviet nuclear-powered submarine that had a reactor accident on August 10, 1985. An explosion occurred during refueling of the submarine at Chazhma Bay, Vladivostok...

 accident in 1985 resulted in 10 fatalities and 49 other people suffered radiation injuries.

Alternative propulsion

Oil-fired steam turbines powered the British K-class submarines
British K class submarine
The K class submarines were a class of steam-propelled submarines of the Royal Navy designed in 1913. Intended as large, fast vessels which had the endurance and speed to operate with the battle fleet, they gained notoriety, and the nickname of Kalamity class, for being involved in many accidents....

, built during the first World War
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

 and later, to give them the surface speed to keep up with the battle fleet. The K-class subs were not very successful, however.

Toward the end of the 20th century, some submarines, such as the British Vanguard class, began to be fitted with pump-jet
Pump-jet
A pump-jet, hydrojet, or water jet, is a marine system that creates a jet of water for propulsion. The mechanical arrangement may be a ducted propeller with nozzle, or a centrifugal pump and nozzle...

 propulsors instead of propellers. Although these are heavier, more expensive, and less efficient than a propeller, they are significantly quieter, giving an important tactical advantage.

Magnetohydrodynamic drive
Magnetohydrodynamic drive
A magnetohydrodynamic drive or MHD propulsor is a method for propelling seagoing vessels using only electric and magnetic fields with no moving parts, using magnetohydrodynamics. The working principle involves electrification of the propellant which can then be directed by a magnetic field,...

 (MHD) was portrayed as the operating principle behind the titular submarine's nearly silent propulsion system in the film adaptation
The Hunt for Red October (film)
The Hunt for Red October is a 1990 thriller film based on the novel of the same name by Tom Clancy. It was directed by John McTiernan and stars Sean Connery as Captain Marko Ramius and Alec Baldwin as Jack Ryan...

 of The Hunt for Red October
The Hunt for Red October
The Hunt for Red October is a 1984 novel by Tom Clancy. The story follows the intertwined adventures of Soviet submarine captain Marko Aleksandrovich Ramius and CIA analyst Jack Ryan.The novel was originally published by the U.S...

. However, in the novel, the Red October did not use MHD. Although experimental surface ships have used this system, speeds have been below expectations. In addition, the drive system can induce bubble formation, compromising stealth, and the low efficiency requires high powered reactors. These factors make it unlikely for military usage.

Armament

The success of the submarine is inextricably linked to the development of the torpedo
Torpedo
The modern torpedo is a self-propelled missile weapon with an explosive warhead, launched above or below the water surface, propelled underwater towards a target, and designed to detonate either on contact with it or in proximity to it.The term torpedo was originally employed for...

, invented by Robert Whitehead
Robert Whitehead
Robert Whitehead was an English engineer. He developed the first effective self-propelled naval torpedo. His company, located in the Austrian naval centre in Fiume, was the world leader in torpedo development and production up to the First World War.- Early life:He was born the son of a...

 in 1866. His invention is essentially the same now as it was 140 years ago. Only with self propelled torpedoes could the submarine make the leap from novelty to a weapon of war. Until the perfection of the guided torpedo
Acoustic torpedo
An acoustic torpedo is a torpedo that aims itself by listening for characteristic sounds of its target or by searching for it using sonar. Acoustic torpedoes are usually designed for medium-range use, and often fired from a submarine....

, multiple "straight-running" torpedoes were required to attack a target. With at most 20 to 25 torpedoes stored onboard, the number of attacks was limited. To increase combat endurance
Combat endurance
Combat endurance is the time for which a military system can remain in combat before having to withdraw due to depleted resources. The definition is not precise; for example the combat endurance of an aircraft, without qualification, is usually the time the aircraft can remain at an altitude...

 most World War I submarines functioned as submersible gunboats, using their deck guns against unarmed targets, and diving to escape and engage enemy warships. The importance of guns encouraged the development of the unsuccessful Submarine Cruiser such as the French Surcouf
Surcouf (N N 3)
Surcouf was a French submarine ordered to be built in December 1927, launched on 18 October 1929, and commissioned in May 1934. Surcouf—named after the French privateer Robert Surcouf—was the largest submarine ever built until surpassed by the Japanese I-400s. Her short wartime career was marked...

and the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

's X1
HM Submarine X1
HM Submarine X1 was conceived and designed as a submersible commerce raider for the Royal Navy; at the time of her launching she was the largest submarine in the world. The idea of a submarine cruiser had been proposed as early as 1915, but was not put into practice until 1921...

and M-class
British M class submarine
The British Royal Navy M-class submarines were a small class of diesel electric submarine built during World War I. The unique feature of the class was a 12-inch gun mounted in a turret forward of the conning tower.-Background:...

 submarines. With the arrival of ASW
Anti-submarine warfare
Anti-submarine warfare is a branch of naval warfare that uses surface warships, aircraft, or other submarines to find, track and deter, damage or destroy enemy submarines....

 aircraft, guns became more for defense than attack. A more practical method of increasing combat endurance was the external torpedo tube, loaded only in port.

The ability of submarines to approach enemy harbours covertly led to their use as minelayers. Minelaying submarines of World War I and World War II were specially built for that purpose. Modern submarine-laid mines
Naval mine
A naval mine is a self-contained explosive device placed in water to destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, an enemy vessel...

, such as the British Mark 6 Sea Urchin, are designed to be deployed by a submarine's torpedo tubes.

After World War II, both the US and the USSR experimented with submarine launched cruise missile
Cruise missile
A cruise missile is a guided missile that carries an explosive payload and is propelled, usually by a jet engine, towards a land-based or sea-based target. Cruise missiles are designed to deliver a large warhead over long distances with high accuracy...

s such as the SSM-N-8 Regulus
SSM-N-8 Regulus
The SSM-N-8A Regulus was a ship and submarine launched, nuclear armed cruise missile deployed by the United States Navy from 1955 to 1964.-Design and development:...

 and P-5 Pyatyorka. Such missiles required the submarine to surface to fire its missiles. They were the forerunners of modern submarine launched cruise missiles, which can be fired from the torpedo tubes of submerged submarines, for example the US BGM-109 Tomahawk
BGM-109 Tomahawk
The Tomahawk is a long-range, all-weather, subsonic cruise missile. Introduced by General Dynamics in the 1970s, it was designed as a medium- to long-range, low-altitude missile that could be launched from a surface platform. It has been improved several times and, by way of corporate divestitures...

 and Russian RPK-2 Viyuga and versions of surface to surface anti-ship missile
Anti-ship missile
Anti-ship missiles are guided missiles that are designed for use against ships and large boats. Most anti-ship missiles are of the sea-skimming type, many use a combination of inertial guidance and radar homing...

s such as the Exocet
Exocet
The Exocet is a French-built anti-ship missile whose various versions can be launched from surface vessels, submarines, helicopters and fixed wing aircraft. Hundreds were fired in combat during the 1980s.-Etymology:...

 and Harpoon
Boeing Harpoon
The Harpoon is an all-weather, over-the-horizon, anti-ship missile system, developed and manufactured by McDonnell Douglas . In 2004, Boeing delivered the 7,000th Harpoon unit since the weapon's introduction in 1977...

, encapsulated for submarine launch. Ballistic missiles can also be fired from a submarine's torpedo tubes, for example missiles such as the anti-submarine SUBROC. With internal volume as limited as ever and the desire to carry heavier warloads, the idea of the external launch tube was revived, usually for encapsulated missiles, with such tubes being placed between the internal pressure and outer streamlined hulls.

The strategic mission of the SSM-N-8 and the P-5 were taken up by submarine-launched ballistic missile
Submarine-launched ballistic missile
A submarine-launched ballistic missile is a ballistic missile capable of delivering a nuclear warhead that can be launched from submarines. Modern variants usually deliver multiple independently targetable reentry vehicles each of which carries a warhead and allows a single launched missile to...

 beginning with the US Navy's Polaris
UGM-27 Polaris
The Polaris missile was a two-stage solid-fuel nuclear-armed submarine-launched ballistic missile built during the Cold War by Lockheed Corporation of California for the United States Navy....

 missile, and subsequently the Poseidon and Trident missiles.

Germany is working on the short-range IDAS (missile)
IDAS (missile)
For other uses, see Idas .IDAS is a short-range missile currently being developed for the new Type 212 submarine class of the German Navy....

 which is launched from a torpedo tube and can be used against ASW helicopters as well as surface ships and coastal targets.

Sensors

A submarine will have a variety of sensors determined by its missions. Modern military submarines rely almost entirely on a suite of passive and active sonar
Sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

s to find their prey. Active sonar relies on an audible "ping" to generate echoes to reveal objects around the submarine. Active systems are rarely used, as doing so reveals the sub's presence. Passive sonar is a set of sensitive hydrophones set into the hull or trailed in a towed array, generally several hundred feet long. The towed array is the mainstay of NATO submarine detection systems, as it reduces the flow noise heard by operators. Hull mounted sonar is employed to back up the towed array, and in confined waters where a towed array could be fouled by obstacles.

Submarines also carry radar equipment for detection of surface ships and aircraft. Sub captains are more likely to use radar detection gear rather than active radar to detect targets, as radar can be detected far beyond its own return range, revealing the submarine. Periscopes are rarely used, except for position fixes and to verify a contact's identity.

Civilian submarines, such as the DSV Alvin
DSV Alvin
Alvin is a manned deep-ocean research submersible owned by the United States Navy and operated by the Woods Hole Oceanographic Institution in Woods Hole, Massachusetts. The vehicle was built by General Mills' Electronics Group in the same factory used to manufacture breakfast cereal-producing...

 or the Russian Mir submersibles
MIR (submersible)
Mir is a self-propelled Deep Submergence Vehicle. The project was initially developed by the USSR Academy of Sciences along with Design Bureau Lazurith. Later two vehicles were ordered from Finland...

, rely on small active sonar sets and viewing ports to navigate. Sunlight does not penetrate below about 300 feet (91.4 m) underwater, so high intensity lights are used to illuminate the viewing area.

Navigation

Early submarines had few navigation aids, but modern subs have a variety of navigation systems. Modern military submarines use an inertial guidance system for navigation while submerged, but drift error unavoidably builds up over time. To counter this, the Global Positioning System
Global Positioning System
The Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...

 will occasionally be used to obtain an accurate position. The periscope
Periscope
A periscope is an instrument for observation from a concealed position. In its simplest form it consists of a tube with mirrors at each end set parallel to each other at a 45-degree angle....

 - a retractable tube with prism
Prism (optics)
In optics, a prism is a transparent optical element with flat, polished surfaces that refract light. The exact angles between the surfaces depend on the application. The traditional geometrical shape is that of a triangular prism with a triangular base and rectangular sides, and in colloquial use...

s allowing a view to the surface - is only used occasionally in modern submarines, since the range of visibility is short. The Virginia-class submarines
Virginia class submarine
The Virginia class is a class of nuclear-powered fast attack submarines in service with the United States Navy. The submarines are designed for a broad spectrum of open-ocean and littoral missions...

 and Astute-class submarines
Astute class submarine
The Astute-class is the latest class of nuclear-powered fleet submarines in service with the Royal Navy. The class sets a new standard for the Royal Navy in terms of weapons load, communication facilities and stealth. The boats are being constructed by BAE Systems Submarine Solutions at...

 have photonics mast
Photonics mast
A photonics mast is a sensor similar in concept to a submarine periscope, except that it doesn't require a periscope tube thus freeing design space duringconstruction and limiting risks of water leakage in the event of damage...

s rather than hull-penetrating optical periscopes. These masts must still be hoisted above the surface, and employ electronic sensors for visible light, infrared, laser range-finding, and electromagnetic surveillance. One benefit to hoisting the mast above the surface is that while the mast is above the water the entire sub is still below the water and is much harder to detect visibly or by radar.

Communication

Military submarines have several systems for communicating with distant command centers or other ships. One is VLF (Very Low Frequency) radio, which can reach a submarine either on the surface or submerged to a fairly shallow depth, usually less than 250 feet (76.2 m). ELF
Extremely low frequency
Extremely low frequency is a term used to describe radiation frequencies from 3 to 300 Hz. In atmosphere science, an alternative definition is usually given, from 3 Hz to 3 kHz...

 (Extremely Low Frequency) can reach a submarine at much greater depths, but has a very low bandwidth and are generally used to call a submerged sub to a shallower depth where VLF signals can reach. A submarine also has the option of floating a long, buoyant wire antenna to a shallower depth, allowing VLF transmissions to be made by a deeply submerged boat.

By extending a radio mast, a submarine can also use a "burst transmission
Burst transmission
In telecommunication, the term burst transmission or data burst has the following meanings:# Any relatively high-bandwidth transmission over a short period of time...

" technique. A burst transmission takes only a fraction of a second, minimizing a submarine's risk of detection.

To communicate with other submarines, a system known as Gertrude is used. Gertrude is basically a sonar telephone
Underwater telephone
The underwater telephone also known as UQC , or Gertrude wasdeveloped by the U.S. Navy in 1945 , the UQC underwater telephone is used on all manned submersibles in operation. Voices communicated through the UQC are heterodyned to a high pitch for acoustic transmission through water....

. Voice communication from one submarine is transmitted by low power speakers into the water, where it is detected by passive sonars on the receiving submarine. The range of this system is probably very short, and using it radiates sound into the water, which can be heard by the enemy.

Civilian submarines can use similar, albeit less powerful systems to communicate with support ships or other submersibles in the area.

Crew

A typical nuclear submarine has a crew of over 80. Non-nuclear boats typically have fewer than half as many. The conditions on a submarine can be difficult because crew members must work in isolation for long periods of time, without family contact. Submarines normally maintain radio silence
Radio silence
In telecommunications, radio silence is a status in which all fixed or mobile radio stations in an area are asked to stop transmitting for safety or security reasons.The term "radio station" may include anything capable of transmitting a radio signal....

 to avoid detection. Operating a submarine is dangerous, even in peacetime, and many submarines have been lost in accidents.

Women as part of crew

Most navies prohibited women from serving on submarines, even after they had been permitted to serve on surface warships. The Royal Norwegian Navy
Royal Norwegian Navy
The Royal Norwegian Navy is the branch of the Norwegian Defence Force responsible for naval operations. , the RNoN consists of approximately 3,700 personnel and 70 vessels, including 5 heavy frigates, 6 submarines, 14 patrol boats, 4 minesweepers, 4 minehunters, 1 mine detection vessel, 4 support...

 became the first navy to allow female crew on its submarines in 1985. The Royal Danish Navy
Royal Danish Navy
The Royal Danish Navy is the sea-based branch of the Danish Defence force. The RDN is mainly responsible for maritime defence and maintaining the sovereignty of Danish, Greenlandic and Faroese territorial waters...

 allowed female submariners in 1988. Others followed suit including the Swedish Navy
Swedish Navy
The Royal Swedish Navy is the naval branch of the Swedish Armed Forces. It is composed of surface and submarine naval units – the Fleet – as well as marine units, the so-called Amphibious Corps .In Swedish, vessels of the Swedish Navy are given the prefix "HMS," short for Hans/Hennes...

 (1989), the Royal Australian Navy
Royal Australian Navy
The Royal Australian Navy is the naval branch of the Australian Defence Force. Following the Federation of Australia in 1901, the ships and resources of the separate colonial navies were integrated into a national force: the Commonwealth Naval Forces...

 (1998), the German Navy
German Navy
The German Navy is the navy of Germany and is part of the unified Bundeswehr .The German Navy traces its roots back to the Imperial Fleet of the revolutionary era of 1848 – 52 and more directly to the Prussian Navy, which later evolved into the Northern German Federal Navy...

 (2001) and the Canadian Navy
Royal Canadian Navy
The history of the Royal Canadian Navy goes back to 1910, when the naval force was created as the Naval Service of Canada and renamed a year later by King George V. The Royal Canadian Navy is one of the three environmental commands of the Canadian Forces...

 (2002). In 1995, Solveig Krey
Solveig Krey
Solveig Krey is a Norwegian naval officer.She hails from Lonkan, and graduated from the Norwegian Naval Academy in 1989. She became the first female commanding officer of a submarine in the world, when she took command of HNoMS Kobben, the lead ship of her class of Royal Norwegian Navy submarines,...

 of the Royal Norwegian Navy
Royal Norwegian Navy
The Royal Norwegian Navy is the branch of the Norwegian Defence Force responsible for naval operations. , the RNoN consists of approximately 3,700 personnel and 70 vessels, including 5 heavy frigates, 6 submarines, 14 patrol boats, 4 minesweepers, 4 minehunters, 1 mine detection vessel, 4 support...

 became the first female officer to assume command on a military submarine, HNoMS Kobben.

The British Royal Navy does not permit women to serve on its submarines because of "medical concerns for the safety of the fetus and hence its mother" due to the potentially compromised air quality onboard submarines. Similar dangers to the pregnant woman and her fetus barred females from submarine service in Sweden 1983, when all other positions were made available for them in the Swedish Navy. Pregnant women are still not allowed to serve on submarines in Sweden. However, the policy makers thought that it was discriminatory with a general ban and demanded that females should be tried on their individual merits and have their suitability evaluated and compared to other candidates. Further, they noted that a female complying with such high demands is unlikely to become pregnant unawares.

Women have served on U.S. Navy surface ships since 1993, and will begin serving on submarines for the first time. Until presently, the Navy only allowed three exceptions for women being on board military submarines: female civilian technicians for a few days at most, women midshipmen
Midshipman
A midshipman is an officer cadet, or a commissioned officer of the lowest rank, in the Royal Navy, United States Navy, and many Commonwealth navies. Commonwealth countries which use the rank include Australia, New Zealand, South Africa, India, Pakistan, Singapore, Sri Lanka and Kenya...

 on an overnight during summer training for both Navy ROTC and Naval Academy
United States Naval Academy
The United States Naval Academy is a four-year coeducational federal service academy located in Annapolis, Maryland, United States...

, and family members for one-day dependent cruises. In 2009, senior officials, including then-Secretary of the Navy Ray Mabus
Ray Mabus
Raymond Edwin "Ray" Mabus, Jr. is the 75th United States Secretary of the Navy. Mabus served as the 60th Governor of the U.S...

, Joint Chief of Staff Admiral Michael Mullen
Michael Mullen
Michael Glenn "Mike" Mullen is a retired United States Navy four-star admiral, who served as the 17th Chairman of the Joint Chiefs of Staff from October 1, 2007 to September 30, 2011. Mullen previously served as the Navy's 28th Chief of Naval Operations from July 22, 2005 to September 29, 2007...

, and Chief of Naval Operations Admiral Gary Roughead
Gary Roughead
Gary Roughead is a retired United States Navy four-star admiral who last served as the 29th Chief of Naval Operations from September 29, 2007 to September 22, 2011. He previously served as Commander, U.S. Fleet Forces Command, from May 17, 2007, to September 29, 2007. Prior to that he served as...

, began the process of finding a way to implement females onboard submarines. In 2011, the first classes of female submarine officers graduated from Naval Submarine School's Submarine Officer Basic Course (SOBC) at the Naval Submarine Base New London
Naval Submarine Base New London
Naval Submarine Base New London is the United States Navy's primary submarine base, the "Home of the Submarine Force", and "the Submarine Capital of the World".-History:...

. Additionally, more senior ranking and experienced female supply officers from the surface warfare specialty will attend SOBC as well, and proceed to fleet Ballistic Missile (SSBN) and Guided Missile (SSGN) submarines along with the new female submarine line officers beginning in late 2011/early 2012.

Both the U.S. and British navies operate nuclear-powered submarines which deploy for periods of six months or longer, whereas the other navies that do permit women to serve on submarines operate conventionally powered submarines, which deploy for much shorter periods, usually only for one or two months. Prior the recent change by the U.S., no nation using nuclear submarines permitted women to serve onboard them.

Life support systems

With nuclear power
Nuclear reactor
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...

, submarines can remain submerged for months at a time. Diesel submarines must periodically resurface or snorkel
Submarine snorkel
A submarine snorkel is a device which allows a submarine to operate submerged while still taking in air from above the surface. Navy personnel often refer to it as the snort.-History:...

 to recharge their batteries. Most modern military submarines generate breathing oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 by electrolysis
Electrolysis
In chemistry and manufacturing, electrolysis is a method of using a direct electric current to drive an otherwise non-spontaneous chemical reaction...

 of water. Atmosphere control equipment includes a CO2
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 scrubber, which uses an amine
Amine gas treating
Amine gas treating, also known as gas sweetening and acid gas removal, refers to a group of processes that use aqueous solutions of various alkylamines to remove hydrogen sulfide and carbon dioxide from gases...

 absorbent to remove the gas from air and diffuse it into waste pumped overboard. A machine that uses a catalyst to convert carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

 into carbon dioxide (removed by the CO2 scrubber) and bonds hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 produced from the ship's storage battery with oxygen in the atmosphere to produce water, is also used. An atmosphere monitoring system samples the air from different areas of the ship for nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

, oxygen, hydrogen, R-12
Dichlorodifluoromethane
Dichlorodifluoromethane , is a colorless gas, and usually sold under the brand name Freon-12, is a chlorofluorocarbon halomethane , used as a refrigerant and aerosol spray propellant. Complying with the Montreal Protocol, its manufacture was banned in the United States along with many other...

 and R-114
1,2-Dichlorotetrafluoroethane
1,2-Dichlorotetrafluoroethane, or R-114, is a chlorofluorocarbon with the molecular formula ClF2CCF2Cl. Its primary use has been as a refrigerant. It is a non-flammable gas with a sweetish, chloroform-like odor with critical point at 145.6 °C and 3.26 MPa. When pressurized or cooled,...

 refrigerants, carbon dioxide, carbon monoxide
Carbon monoxide
Carbon monoxide , also called carbonous oxide, is a colorless, odorless, and tasteless gas that is slightly lighter than air. It is highly toxic to humans and animals in higher quantities, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal...

, and other gases. Poisonous gases are removed, and oxygen is replenished by use of an oxygen bank located in a main ballast tank. Some heavier submarines have two oxygen bleed stations (forward and aft). The oxygen in the air is sometimes kept a few percent less than atmospheric concentration to reduce fire danger.

Fresh water is produced by either an evaporator or a reverse osmosis
Reverse osmosis
Reverse osmosis is a membrane technical filtration method that removes many types of large molecules and ions from solutions by applying pressure to the solution when it is on one side of a selective membrane. The result is that the solute is retained on the pressurized side of the membrane and...

 unit. The primary use for fresh water is to provide feed water for the reactor and steam propulsion plants. It is also available for showers, sinks, cooking and cleaning once propulsion plant needs have been met. Seawater is used to flush toilets, and the resulting "black water
Blackwater (waste)
Blackwater is a term dating to at least the 1970s used to describe wastewater containing fecal matter and urine. It is also known as brown water, foul water, or sewage...

" is stored in a sanitary tank until it is blown overboard using pressurized air or pumped overboard by using a special sanitary pump. The method for blowing sanitaries overboard is difficult to operate, and the German Type VIIC boat U-1206
German submarine U-1206 (1944)
German submarine U-1206 was a German Type VIIC U-boat of the Kriegsmarine during World War II. She was laid down on June 12, 1943 at F. Schichau GmbH in Danzig and went into service on March 16, 1944. The boat's emblem was a white Stork on a black shield with green beak and legs.-Service...

 was lost with casualties because of a mistake with the toilet. Water from showers and sinks is stored separately in "grey water
Greywater
Greywater is wastewater generated from domestic activities such as laundry, dishwashing, and bathing, which can be recycled on-site for uses such as landscape irrigation and constructed wetlands...

" tanks, which are pumped overboard using the drain pump.

Trash on modern large submarines is usually disposed of using a tube called a Trash Disposal Unit (TDU), where it is compacted into a galvanized steel can. At the bottom of the TDU is a large ball valve. An ice plug is set on top of the ball valve to protect it, the cans atop the ice plug. The top breech door is shut, and the TDU is flooded and equalized with sea pressure, the ball valve is opened and the cans fall out assisted by scrap iron weights in the cans. The TDU is also flushed with seawater to ensure it is completely empty and the ball valve is clear before shutting the valve.

See also

  • Autonomous underwater vehicle
    Autonomous Underwater Vehicle
    An autonomous underwater vehicle is a robot which travels underwater without requiring input from an operator. AUVs constitute part of a larger group of undersea systems known as unmanned underwater vehicles, a classification that includes non-autonomous remotely operated underwater vehicles...

  • Deep Submergence Rescue Vehicle
    Deep Submergence Rescue Vehicle
    A Deep Submergence Rescue Vehicle is a type of Deep Submergence Vehicle used for rescue of downed submarines and clandestine missions. While DSRV is the term most often used by the United States Navy other nations have different designations for their vehicles.- Chinese models :The People's...

  • List by death toll of ships sunk by submarines
  • List of countries with submarines
  • List of submarine actions
  • List of submarine museums
  • List of sunken nuclear submarines
  • Merchant submarine
    Merchant submarine
    A merchant submarine is a type of submarine intended for trade, and being without armaments, it is not considered a warship like most other types of submarines...

  • Submarines in the United States Navy
    Submarines in the United States Navy
    There are two major types of submarines in the United States Navy: ballistic missile submarines and attack submarines. In the U.S. Navy, all combatant submarines are nuclear-powered. Ballistic subs have a single, strategic mission: carrying nuclear submarine-launched ballistic missiles...

  • Submarine films
  • Submarine simulator
    Submarine simulator
    A submarine simulator, or subsim for short, is usually a computer game in which the player commands a submarine. The usual form of the game is to go on a series of missions, each of which features a number of encounters where the goal is to sink surface ships and to survive counterattacks by...

    , a computer game genre
  • Submarine warfare
    Submarine warfare
    Naval warfare is divided into three operational areas: surface warfare, air warfare and underwater warfare. The latter may be subdivided into submarine warfare and anti-submarine warfare as well as mine warfare and mine countermeasures...

  • Naval Submarine Medical Research Laboratory
    Naval Submarine Medical Research Laboratory
    The Naval Submarine Medical Research Laboratory is located on the New London Submarine Base in Groton, Connecticut. The laboratory's mission is to protect the health and enhance the performance of United States War Fighters through focused submarine, diving, and surface research solutions.-History...

     (United States)

:Category:Fictional submarines

Related topics

  • Depth charge
    Depth charge
    A depth charge is an anti-submarine warfare weapon intended to destroy or cripple a target submarine by the shock of exploding near it. Most use explosives and a fuze set to go off at a preselected depth in the ocean. Depth charges can be dropped by either surface ships, patrol aircraft, or from...

  • Timeline of underwater technology
    Timeline of underwater technology
    This is a timeline of underwater technology.The entries marked ## are about decompression tables.-Pre-industrial:* Several centuries BC: This is a timeline of underwater technology.The entries marked ## are about decompression tables.-Pre-industrial:* Several centuries BC: This is a timeline of...

  • Modern Naval tactics
    Modern naval tactics
    The term modern naval tactics refers to tactical doctrines developed after World War II, following the final obsolescence of the battleship and the development of long-range missiles. Since there has been no major naval conflict since World War II, with the exception of the Falklands War, many of...

  • Nuclear navy
    Nuclear navy
    Nuclear navy, or nuclear powered navy consists of ships powered by relatively small onboard nuclear reactors known as naval reactors. The concept was revolutionary for naval warfare when first proposed, as it meant that these vessels did not need to stop for fuel like their conventional...

  • Submarine communications cable
    Submarine communications cable
    A submarine communications cable is a cable laid on the sea bed between land-based stations to carry telecommunication signals across stretches of ocean....

  • Submarine power cable
    Submarine power cable
    Submarine power cables are major transmission cables for carrying electric power below the surface of the water. These are called "submarine" because they usually carry electric power beneath salt water but it is also possible to use submarine power cables beneath fresh water...

  • Submersible
    Submersible
    A submersible is a small vehicle designed to operate underwater. The term submersible is often used to differentiate from other underwater vehicles known as submarines, in that a submarine is a fully autonomous craft, capable of renewing its own power and breathing air, whereas a submersible is...

  • Semi-submersible
    Semi-submersible
    A semi-submersible is a specialised marine vessel with good stability and seakeeping characteristics. The semi-submersible vessel design is commonly used in a number of specific offshore roles such as for offshore drilling rigs, safety vessels, oil production platforms and heavy lift cranes.The...

  • Submarine Voyage
    Submarine Voyage
    The Submarine Voyage thru liquid space was an attraction at Disneyland in Anaheim, California.The attraction, which featured ride vehicles designed to look like Navy nuclear submarines, opened on June 14, 1959...

  • Midget submarine
    Midget submarine
    A midget submarine is any submarine under 150 tons, typically operated by a crew of one or two but sometimes up to 6 or 8, with little or no on-board living accommodation...


Articles on specific vessels


Articles on specific submarine classes


External links

- Submarine boat
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