Cave diving - AbsoluteAstronomy.com

Cave diving is a type of technical diving

Technical diving

Technical diving is a form of scuba diving that exceeds the scope of recreational diving...

Scuba set

A scuba set is an independent breathing set that provides a scuba diver with the breathing gas necessary to breathe underwater during scuba diving. It is much used for sport diving and some sorts of work diving....

is used to enable the exploration of cave

Cave

A cave or cavern is a natural underground space large enough for a human to enter. The term applies to natural cavities some part of which is in total darkness. The word cave also includes smaller spaces like rock shelters, sea caves, and grottos.Speleology is the science of exploration and study...

s which are at least partially filled with water. In the United Kingdom it is an extension of the more common sport of caving

Caving

Caving—also occasionally known as spelunking in the United States and potholing in the United Kingdom—is the recreational pastime of exploring wild cave systems...

, and in the United States an extension of the more common sport of SCUBA

Scuba diving

Scuba diving is a form of underwater diving in which a diver uses a scuba set to breathe underwater....

diving. Compared to caving and SCUBA diving, there are relatively few practitioners of cave diving. This is due in part to the specialized equipment (such as rebreather

Rebreather

A rebreather is a type of breathing set that provides a breathing gas containing oxygen and recycled exhaled gas. This recycling reduces the volume of breathing gas used, making a rebreather lighter and more compact than an open-circuit breathing set for the same duration in environments where...

s, diver propulsion vehicle

Diver Propulsion Vehicle

A diver propulsion vehicle is an item of diving equipment used by scuba and rebreather divers to increase range underwater...

s and dry suit

Dry suit

A dry suit or drysuit provides thermal insulation or passive thermal protection to the wearer while immersed in water, and is worn by divers, boaters, water sports enthusiasts, and others who work or play in or near cold water. A dry suit normally protects the whole body except the head, hands, and...

s) and skill sets required, and in part because of the high potential risks, including decompression sickness

Decompression sickness

Decompression sickness describes a condition arising from dissolved gases coming out of solution into bubbles inside the body on depressurization...

and drowning

Drowning

Drowning is death from asphyxia due to suffocation caused by water entering the lungs and preventing the absorption of oxygen leading to cerebral hypoxia....

.

Despite these risks, water-filled caves attract SCUBA divers, cavers

Caving

Caving—also occasionally known as spelunking in the United States and potholing in the United Kingdom—is the recreational pastime of exploring wild cave systems...

, and speleologists

Speleology

Speleology is the scientific study of caves and other karst features, their make-up, structure, physical properties, history, life forms, and the processes by which they form and change over time...

due to their often unexplored nature, and present divers

Underwater diving

Underwater diving is the practice of going underwater, either with breathing apparatus or by breath-holding .Recreational diving is a popular activity...

with a technical diving challenge. Underwater caves have a wide range of physical features, and can contain fauna

Stygofauna

Stygofauna are any fauna that live within groundwater systems, such as caves and aquifers, or more specifically small, aquatic groundwater invertebrates, though terrestrial air-breathing subterranean animals are also sometimes included...

not found elsewhere.

Hazards

Cave diving is one of the most challenging and potentially dangerous kinds of diving or caving and presents many hazards

Diving hazards and precautions

Divers face specific physical and health risks when they go underwater or use high pressure breathing gases. Some of these conditions also affect people who work in raised pressure environments out of water, e.g...

. Cave diving is a form of penetration diving

Penetration diving

Penetration diving or no clear surface diving is a type of diving where the scuba diver enters a space from which there is no direct, purely vertical ascent to the safety of breathable air of the atmosphere at the surface...

, meaning that in an emergency a diver cannot swim vertically to the surface due to the cave's ceilings, and so must swim the entire way back out in case of emergency. The underwater navigation through the cave system may be difficult and exit routes may be at considerable distance, requiring the diver to have sufficient breathing gas

Breathing gas

Breathing gas is a mixture of gaseous chemical elements and compounds used for respiration.Air is the most common and only natural breathing gas...

to make the journey. The dive may also be deep, resulting in potential deep diving

Deep diving

The meaning of the term deep diving is a form of technical diving. It is defined by the level of the diver's diver training, diving equipment, breathing gas, and surface support:...

risks.

Visibility can vary from nearly unlimited to low, or non-existent, and can go from one extreme to the other in a single dive. While a less-intensive kind of diving called cavern diving does not take divers beyond the reach of natural light (and typically no deeper than 100 ft, and penetration not further than 200 ft), true cave diving can involve penetrations of many thousands of feet, well beyond the reach of sunlight. The level of darkness experienced creates an environment impossible to see in without an artificial form of light. Caves often contain sand, mud, clay, silt, or other sediment that can further reduce underwater visibility in seconds when stirred up.

Caves can carry strong water currents. Most caves emerge on the surface as either springs

Spring (hydrosphere)

A spring—also known as a rising or resurgence—is a component of the hydrosphere. Specifically, it is any natural situation where water flows to the surface of the earth from underground...

or siphon

Siphon

The word siphon is sometimes used to refer to a wide variety of devices that involve the flow of liquids through tubes. But in the English language today, the word siphon usually refers to a tube in an inverted U shape which causes a liquid to flow uphill, above the surface of the reservoir,...

s. Springs have out flowing currents, where water is coming up out of the Earth and flowing out across the land's surface. Siphons have in-flowing currents where, for example, an above-ground river is going underground. Some caves are complex and have some tunnels with out-flowing currents, and other tunnels with in-flowing currents. If currents are not properly managed, they can cause serious problems for the diver.

Cave diving has been perceived as one of the more deadly sports in the world. This perception is arguable because the vast majority of divers who have lost their lives in caves have either not undergone specialized training or have had inadequate equipment for the environment. Cave divers have suggested that cave diving is in fact statistically much safer than recreational diving due to the much larger barriers imposed by experience, training, and equipment cost.

There is no reliable worldwide database listing all cave diving fatalities. Such fractional statistics as are available, however, suggest that very few divers have ever died while following accepted protocols and while using equipment configurations recognized as acceptable by the cave diving community. In the very rare cases of exceptions to this rule there have typically been unusual circumstances.

Safety

Most cave divers recognize five general rules or contributing factors for safe cave diving, which were popularized, adapted and became generally accepted from Sheck Exley

Sheck Exley

-Biography:Exley is widely regarded as one of the pioneers of cave diving, writing two major books on the subject: Basic Cave Diving: A Blueprint for Survival and Caverns Measureless to Man published by Cave Books, , and establishing many of the basic safety procedures used in cave and overhead...

's 1977 publication Basic Cave Diving: A Blueprint for Survival. In this book, Exley included accounts of actual cave diving accidents, and followed each one with a breakdown of what factors contributed to the accident. Despite the uniqueness of any individual accident, Exley found that at least one of a small number of major factors contributed to each one. This technique for breaking down accident reports and finding common causes among them is now called Accident Analysis, and is taught in introductory cave diving courses. Exley outlined a number of these resulting cave diving rules, but today these five are the most recognized:

Training: A safe cave diver never exceeds the boundaries of his/her training. Cave diving is normally taught in segments, each successive segment focusing on more complex aspects of cave diving. Furthermore, each segment of training must be coupled with real world experience before moving to a more advanced level. Accident analysis of recent cave diving fatalities has proven that academic training without sufficient real world experience is not enough in the event of an underwater emergency. Only by slowly building experience can one remain calm enough to recall their training should a problem arise, whereas an inexperienced diver (who may be recently trained) will tend to panic when confronted with a similar situation.

Guide line
Distance line
A distance line, penetration line or guideline is an item of diving equipment used by SCUBA divers as a means of returning to a safe starting point in conditions of low visibility, water currents or where pilotage is difficult...

: A continuous guide line is maintained at all times between the leader of a dive team and a fixed point selected outside the cave entrance in open water. Often this line is tied off a second time as a backup directly inside the cavern zone. As the dive leader lays the guideline he takes great care to ensure there is sufficient tension on the line. Should a silt out
Silt out
A silt out is a situation when underwater visibility is rapidly reduced to zero.It often happens from divers' swimfins disturbing silt, particularly in caves or in still fresh water....

occur, divers can find the taut line and successfully follow it back to the cave entrance. It is important to note that not using a continuous guide line to open water is the number one cause of fatality among untrained, non-certified divers who venture into caves.

Depth rules: Gas consumption and decompression obligation increase with depth, and it is critical that no cave diver exceeds the dive plan or the maximum operating depth
Maximum operating depth
In technical diving and nitrox diving, the maximum operating depth of a breathing gas is the depth at which the partial pressure of oxygen of the gas mix exceeds a safe limit...

(MOD) of the gas mixture used. Also, the effects of nitrogen narcosis
Nitrogen narcosis
Narcosis while diving , is a reversible alteration in consciousness that occurs while scuba diving at depth. The Greek word ναρκωσις is derived from narke, "temporary decline or loss of senses and movement, numbness", a term used by Homer and Hippocrates...

are more critical in a cave, even for a diver who has the same depth experience in open water. Cave divers are advised not to dive to "excessive depth," and to keep in mind this effective difference between open water depth and cave depth. It should be noted that among fully trained cave divers' deaths, excessive depth is frequently cited as the cause.

Air (gas) management: The most common protocol is the 'rule of thirds
Rule of thirds (diving)
In scuba diving, the rule of thirds is a rule of thumb that divers use to plan dives so they do not consume all the breathing gas from the diving cylinder before the end of the dive....

,' in which one third of the initial gas supply is used for ingress, one third for egress, and one third to support another team member in the case of an emergency. UK practice is to adhere to the rule of thirds, but with an added emphasis on keeping depletion of your separate air systems "balanced," so that the loss of a complete air system will still leave you with sufficient air to return safely. Note that the rule of thirds makes no allowance for the increased air consumption that the loss of an air system will induce. Dissimilar tank sizes among the divers are also not included and the proper amount of air reserve must be calculated for each dive (if tanks are dissimilar). UK practice is to assume that anyone else diving with you does not exist, as in a typical UK sump there is absolutely nothing that you can do to assist him/her. Most UK cave divers dive solo
Solo diving
Solo diving is the practice of scuba diving alone without a "dive buddy". Solo diving, once discouraged, is now beginning to gain acceptance among experienced divers who have skills in self-sufficiency and redundant backup equipment....

. US sump divers follow a similar protocol. Note that the rule of thirds was devised as an approach to diving Florida's caves - they typically have high outflow currents, which help to reduce air consumption when exiting. In a cave system with little (or no) outflow it is mandatory to reserve more air than is dictated by the rule of thirds.

Lights: All cave divers must have three independent sources of light. One is considered the primary and the other two are considered backup lights. If any one of the three light sources fail for one diver, the dive is called off and ended for all members of the dive team.

These five rules may be remembered with the mnemonic

Mnemonic

A mnemonic , or mnemonic device, is any learning technique that aids memory. To improve long term memory, mnemonic systems are used to make memorization easier. Commonly encountered mnemonics are often verbal, such as a very short poem or a special word used to help a person remember something,...

The Good Divers Are Living, the first letter of each word referring to the first letter of the corresponding rule. An alternative mnemonic taught in the United States is Thank Goodness All Divers Live, requiring a rearrangement of the rules.

In recent years new contributing factors were considered after reviewing accidents involving solo diving, diving with incapable dive partners, video or photography in caves, complex cave dives and cave diving in large groups. With the establishment of technical diving, the usage of mixed gases—such as trimix for bottom gas, and nitrox and 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 decompression—reduces the margin for error. Accident analysis informs us that breathing the wrong gas at the wrong depth and/or not analyzing the breathing gas properly has led to cave diving accidents.

Cave diving requires a wide variety of very specialized techniques. Divers who do not adhere strictly to these techniques, as well as equipment specifications, greatly increase the amount of risk they undertake. The cave diving community works hard to educate the public on the risks they assume when they enter water-filled caves. Warning signs with the likenesses of the Grim Reaper have been placed just inside the openings of many popular caves in the US, and others have been placed in nearby parking lots and local dive shops.

Many cave diving sites around the world contain basins, which are also popular open-water diving sites. These sites try to minimize the risk of untrained divers being tempted to venture inside the cave systems. With the support of the cave diving community, many of these sites enforce a "no-lights rule" for divers who lack cave training—they may not carry any lights into the water with them. It is easy to venture into an underwater cave with a light and not realize how far away from the entrance (and daylight) one has swum; this rule is based on the theory that, without a light, divers will not venture beyond daylight.

Training

Cave diving training includes equipment selection and configuration, guideline protocols and techniques, gas management protocols, communication techniques, propulsion techniques, emergency management protocols, and psychological education. As cave diver training stresses the importance of safety it does point out cave conservation ethics as well. Most training programs contain various stages of certification and education.

Cavern training explains the basic skills needed to enter into the overhead environment. Training will generally consist of gas planning, propulsion
Marine propulsion
Marine propulsion is the mechanism or system used to generate thrust to move a ship or boat across water. While paddles and sails are still used on some smaller boats, most modern ships are propelled by mechanical systems consisting a motor or engine turning a propeller, or less frequently, in jet...

techniques needed to deal with the silty environments in many caves, reel and handling, and communication. Once certified as a cavern diver, a diver may undertake cavern diving with a cavern (or greater) certified "buddy," as well as advance into cave diving training.

Introduction into cave training builds off of the techniques learned during cavern training and includes the training needed to penetrate beyond the cavern zone and working with permanent guidelines that exist in many caves. Once intro to cave certified, a diver may penetrate much further into a cave, usually limited by 1/3 of a single cylinder, or in the case of a basic cave certification, 1/6 of double cylinders. An intro cave diver is usually not certified to do complex navigation.

Apprentice cave training serves as the building block from intro to full certification and includes the training needed to penetrate deep into caves working from both permanent guide lines as well as limited exposure to side lines that exist in many caves. Training covers complex dive planning and decompression procedures used for longer dives. Once apprentice certified, a diver may penetrate much further into a cave, usually limited by 1/3 of double cylinders. An apprentice diver is also allowed to do a single jump or gap (a break in the guideline from two sections of mainline or between mainline and sideline) during the dive. An apprentice diver typically has one year to finish full cave or must repeat the apprentice stage.

Full cave training serves final level of basic training and includes the training needed to penetrate deep into the cave working from both permanent guidelines as well as sidelines and may plan and complete complex dives deep into a system using decompression to stay longer. Once cave certified, a diver may penetrate much further into a cave, usually limited by 1/3 of double cylinders. A cave diver is also allowed to do multiple jumps or gaps (a break in the guideline from two sections of mainline or between mainline and sideline) during the dive.

International differences

The cave diving community is a global one, partly due to the highly specialised nature with the resulting small numbers of practitioners at a local level.

However, cave diving practice can differ markedly by locality. One such difference is the use of a floating polypropylene

Polypropylene

Polypropylene , also known as polypropene, is a thermoplastic polymer used in a wide variety of applications including packaging, textiles , stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymer banknotes...

guide line. Most cave divers in the U.S. balk at the use of any sort of floating guide line, 6 mm polypropylene line is the norm in UK precisely because it does float - the line is regularly anchored to stones, lead weights, or whatever is needed and the floating keeps it clear of mud and silt. In Europe, thinner yet slightly buoyant line is typical. Cave diving practices in some localities may be different than those in other parts of the world because those caves require specialized techniques. It is always recommended that individuals contact someone familiar with a cave before venturing inside a cave.

Regularity in signs and warnings may also differ around the world. For example, warnings signs are rare in the UK.

History

Jacques-Yves Cousteau

Jacques-Yves Cousteau was a French naval officer, explorer, ecologist, filmmaker, innovator, scientist, photographer, author and researcher who studied the sea and all forms of life in water...

, co-inventor of the first SCUBA equipment

Scuba set

, was both the world's first SCUBA diver and the world's first SCUBA cave diver. However, many cave divers penetrated caves prior to the advent of SCUBA with surface supplied UBA through the use of umbilical hoses and compressors. SCUBA diving in all its forms, including cave diving, has advanced in earnest since he introduced the aqua-Lung

Aqua-lung

Aqua-Lung was the original name of the first open-circuit free-swimming underwater breathing set in reaching worldwide popularity and commercial success...

in 1943.

UK history

The Cave Diving Group

Cave Diving Group

The Cave Diving Group is a United Kingdom-based diver training organisation specialising in cave diving.The CDG was founded in 1946 by Graham Balcombe, making it the world's oldest continuing diving club...

(CDG) was established informally in 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...

in 1935 to organise training and equipment for the exploration of flooded caves in the Mendip Hills

Mendip Hills

The Mendip Hills is a range of limestone hills to the south of Bristol and Bath in Somerset, England. Running east to west between Weston-super-Mare and Frome, the hills overlook the Somerset Levels to the south and the Avon Valley to the north...

of Somerset. The first dive was made by Jack Sheppard

Jack Sheppard (cave diver)

Jack Sheppard , born John Arthur Sheppard in Lewisham, Kent , was a pioneer of cave diving in the United Kingdom and a founder of the Cave Diving Group together with Graham Balcombe....

on 4 October 1936,
using a home-made drysuit surface fed from a modified bicycle pump, which allowed Shepard to pass Sump 1 of Swildon's Hole

Swildon's Hole

Swildon's Hole is an extensive cave in Priddy, Somerset. At in length, it is the longest cave on the Mendip Hills. It has been found to be connected to Priddy Green Sink and forms part of the Priddy Caves Site of Special Scientific Interest ....

. Swildon's is an upstream feeder to the Wookey Hole resurgence system. The difficulty of access to the sump in Swildon's prompted operations to move to the resurgence, and the larger cave there allowed use of conventional "hard hat" equipment which was secured from the Siebe Gorman

Siebe Gorman

Siebe Gorman & Company Ltd was a British company which developed diving equipment and breathing equipment and worked on commercial diving and marine salvage projects...

company. The left photograph on the standard diving dress

Standard diving dress

A standard diving dress consists of a metallic diving helmet, an airline or hose from a surface supplied diving air pump, a canvas diving suit, diving knife and boots...

page will give some indication of the scale of operations this entailed. In UK cave diving, the term "Sherpa

Sherpa people

The Sherpa are an ethnic group from the most mountainous region of Nepal, high in the Himalayas. Sherpas migrated from the Kham region in eastern Tibet to Nepal within the last 300–400 years.The initial mountainous migration from Tibet was a search for beyul...

" is used without a drop of irony for the people who carry the diver's gear although recently this has gone out of fashion; support is now more normally used, and before the development of SCUBA equipment such undertakings could be monumental operations.

Diving in the spacious third chamber of Wookey Hole led to a rapid series of advances, each of which was dignified by being given a successive number, until an air surface was reached at what is now known as "Chamber 9." Some of these dives were broadcast live on 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...

radio, which must have been a quite surreal experience for both diver and audience.

The number of sites where standard diving dress

Standard diving dress

A standard diving dress consists of a metallic diving helmet, an airline or hose from a surface supplied diving air pump, a canvas diving suit, diving knife and boots...

could be used is clearly limited and there was little further progress before the outbreak of 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...

reduced the caving community considerably. However, the rapid development of underwater warfare through the war made a lot of surplus equipment

Diving equipment

Diving equipment is equipment used by underwater divers for the purpose of facilitating diving activities. This may be equipment primarily intended for this purpose, or equipment intended for other puprposes which is found to be suitable for diving use....

available. The CDG re-formed in 1946 and progress was rapid. Typical equipment at this time was a frogman

Frogman

A frogman is someone who is trained to scuba diving or swim underwater in a military capacity which can include combat. Such personnel are also known by the more formal names of combat diver or combatant diver or combat swimmer....

rubber diving suit

Diving suit

A diving suit is a garment or device designed to protect a diver from the underwater environment. A diving suit typically also incorporates an air-supply .-History:...

for insulation (water temperature in the UK is typically 4 °C), an oxygen

Oxygen

diving cylinder

Diving cylinder

A diving cylinder, scuba tank or diving tank is a gas cylinder used to store and transport high pressure breathing gas as a component of a scuba set. It provides gas to the scuba diver through the demand valve of a diving regulator....

, soda lime

Soda lime

Soda lime is a mixture of chemicals, used in granular form in closed breathing environments, such as general anaesthesia, submarines, rebreathers and recompression chambers, to remove carbon dioxide from breathing gases to prevent CO2 retention and carbon dioxide poisoning.It is made by treating...

absorbent canister and counter-lung comprising a rebreather

Rebreather

air system and an "AFLOLAUN," meaning "Apparatus For Laying Out Line And Underwater Navigation." The AFLOLAUN consisted of lights, line-reel

Distance line

A distance line, penetration line or guideline is an item of diving equipment used by SCUBA divers as a means of returning to a safe starting point in conditions of low visibility, water currents or where pilotage is difficult...

, compass

Compass

A compass is a navigational instrument that shows directions in a frame of reference that is stationary relative to the surface of the earth. The frame of reference defines the four cardinal directions – north, south, east, and west. Intermediate directions are also defined...

, notebook (for the survey), batteries, and more.

Progress was typically by "bottom walking", as this was considered less dangerous than swimming (note the absence of buoyancy controls). The use of oxygen put a depth limit on the dive, which was considerably mitigated by the extended dive duration. This was the normal diving equipment and methods until approximately 1960 when new techniques using wetsuits (which provide both insulation and buoyancy compensation), twin open-circuit SCUBA air systems the development of side mounting cylinders, helmet-mounted lights and free-swimming with fins. The increasing capacity and pressure rating of air bottles also extended dive durations.

U.S. History

In the 1970s, cave diving greatly increased in popularity among divers in the United States. However, there were very few experienced cave divers and almost no formal classes to handle the surge in interest. The result was a large number of divers trying to cave dive without any formal training. This resulted in more than 100 fatalities over the course of the decade. The state of Florida came close to banning SCUBA diving around the cave entrances. The cave diving organizations responded to the problem by creating training programs and certifying instructors, in addition to other measures to try to prevent these fatalities. This included posting signs, adding no-lights rules, and other enforcements.

In the United States, Sheck Exley

Sheck Exley

was a pioneering cave diver who first explored many Florida

Florida

Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

underwater cave systems, and many other underwater cave systems throughout the US and the world. On February 6, 1974, Exley became the first chairman of the Cave Diving Section of the National Speleological Society

National Speleological Society

The National Speleological Society is an organization formed in 1941 to advance the exploration, conservation, study, and understanding of caves in the United States. Originally located in Washington D.C., its current offices are in Huntsville, Alabama...

.

Since the 1980s, cave diving education has greatly reduced diver fatalities, and it is now rare for an agency trained diver to perish in an underwater cave. Also in the 1980s, refinements were made to the equipment used for cave diving, most importantly better lights with smaller batteries. In the 1990s, cave diving equipment configurations became more standardized, due mostly to the adaptation and popularization of the "Hogarthian Rig", developed by several North Florida cave divers (named in honor of William "Hogarth" Main) which promotes equipment choices that "keep it simple and streamlined".

Today, the cave community is most focused on training, exploration, public awareness, and cave conservation.

Documentary films made by Wesley C. Skiles

Wesley C. Skiles

Wesley C. Skiles was an American cave diving pioneer, explorer, and underwater cinematographer. Skiles lived in High Springs, Florida.-Background:...

and Jill Heinerth have contributed to the increasing popularity of cave diving in the early 21st century.

Grand Bahama Island

The caves and caverns of Grand Bahama

Grand Bahama

Grand Bahama is one of the northernmost of the islands of the Bahamas, and the closest major island to the United States, lying off the state of Florida. Grand Bahama is the fifth largest island in the Bahamas island chain of approximately 700 islands and 2,400 cays...

contain an immense underwater cavern with a vast flooded labyrinth

Labyrinth

In Greek mythology, the Labyrinth was an elaborate structure designed and built by the legendary artificer Daedalus for King Minos of Crete at Knossos...

of caverns, caves and submerged tunnels that honeycomb the entire island of Grand Bahama and the surrounding sea bed. The inland caves are not abundant with life, but do contain creatures living in the caves other than the migrating gray snappers. Residents of these caves include a type of blind cave fish and remipedia

Remipedia

Remipedia is a class of blind crustaceans found in coastal aquifers which contain saline groundwater, with populations identified in almost every ocean basin so far explored, including in Australia, the Caribbean Sea, the Atlantic Ocean...

that don't pose any threat to cave divers.

The caves in the Bahamas were formed during the last ice age

Ice age

An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...

. With much of the Earth's water held in the form of glacial ice, the sea level fell hundreds of feet, leaving most of the Bahama banks, which are now covered in water, high and dry. Rain falling on the most porous limestone slowly filtered down to sea level forming a lens where it contacted the denser salt water of the ocean permeating the spongy lime stone. The water at the interface was acidic enough to dissolve away the limestone and form the caves. Then, as more ice formed and the sea level dropped even further, the caves became dry and rainwater dripping through the ceiling over thousands of years created the incredible crystal forests of stalagmites which now decorate the caves. Finally, when the ice melted and the sea level rose, the caves were reclaimed by the sea.

Central and Northern Florida, U.S.

The largest and most active cave diving community in the United States is in north-central Florida

Florida

. The North Floridan Aquifer

Aquifer

An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...

expels groundwater through numerous first-magnitude springs

Spring (hydrosphere)

A spring—also known as a rising or resurgence—is a component of the hydrosphere. Specifically, it is any natural situation where water flows to the surface of the earth from underground...

, each providing an entrance to the aquifer's labyrinthine cave system. These high-flow springs have resulted in Florida cave divers developing special techniques for exploring them, since some have such strong currents that it is impossible to swim against them.

The longest known underwater cave system in the USA, The Leon Sinks

Leon Sinks

The Leon Sinks Geological Area is located on the Woodville Karst Plain in southern and southwestern Leon County, Florida, United States. It is a mature karstic area on the Upper Floridan Aquifer...

cave system, near Tallahassee, Florida, has multiple interconnected sinks and springs spanning two counties (Leon & Wakulla). One main resurgence of the system, Wakulla Springs

Wakulla Springs

Wakulla Springs is located south of Tallahassee, Florida and east of Crawfordville in Wakulla County, Florida at the crossroads of State Road 61 and State Road 267...

, is explored exclusively by a very successful and pioneering project called the Woodville Karst Plain Project

Woodville Karst Plain Project

The Woodville Karst Plain Project or WKPP, grew out of a cave diving research and exploration group established in 1985 and incorporated in 1990 to map the underwater cave systems underlying the Woodville Karst Plain, a area...

(WKPP), although other individuals and groups like the US Deep Cave Diving Team, have explored portions of Wakulla Springs in the past.

One of the deepest known underwater caves in the USA is Weeki Wachee Spring. Due to its strong outflow, divers have had limited success penetrating this first magnitude spring until 2007, when drought conditions eased the out-flowing water allowing team divers from Karst Underwater Research

Karst Underwater Research

Karst Underwater Research is a 501 not-for-profit organization dedicated to collecting and reporting valuable scientific information from underwater karst environments where scientist are unable to go and providing this information to the public for future generations to better understand and...

to penetrate to depths of 400 ft (121.9 m)

The Florida caves are formed from geologically young limestone

Limestone

Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

with moderate porosity. The absence of speleothem decorations which can only form in air filled caves, indicates that the flooded Florida caves have a single genetic phase origin, having remained water filled even during past low sea levels. In plan form, the caves are relatively linear with a limited number of side passages allowing for most of the guidelines to be simple paths with few permanent tees. It is common practice for cave divers in Florida to joint a main line with a secondary line using a jump reel when exploring side passages, in order to maintain a continuous guideline to the surface.

Yucatan Peninsula, Mexico

While there is great potential for cave diving in the continental karst throughout Mexico, the vast majority of cave diving in Mexico occurs in the Yucatán Peninsula. While there are thousands of deep pit cenotes throughout the Yucatán Peninsula including in the states of Yucatán and Campeche, the extensive sub-horizontal flooded cave networks for which the peninsula is known are essentially limited to a 10 km wide strip of the Caribbean coastline in the state of Quintana Roo extending south from Cancun to the Tulum Municipality and the Sian Ka'an Biosphere Reserve, although some short segments of underwater cave have been explored on the north-west coast (Yucatán State).

In the Yucatán Peninsula, any surface opening where groundwater can be reached is called cenote

Cenote

A cenote is a deep natural pit, or sinkhole, characteristic of Mexico and Central America, resulting from the collapse of limestone bedrock that exposes groundwater underneath...

, which is a Spanish form of the Maya word d’zonot. The cave systems formed as normal caves underwater, but upper sections drained becoming air filled during past low sea levels. During this vadose, or air filled state, abundant speleothem deposits formed. The caves and the vadose speleothem were subsequently reflooded and became hydraulically reactivated as rising sea levels also raised the water table. These caves are therefore polygenetic, having experienced more than one cycle of formation below the water table. Polygenetic coastal cave systems with underwater speleothem are globally common, with notable examples being on the Balearic Islands (Mallorca

Mallorca

Majorca or Mallorca is an island located in the Mediterranean Sea, one of the Balearic Islands.The capital of the island, Palma, is also the capital of the autonomous community of the Balearic Islands. The Cabrera Archipelago is administratively grouped with Majorca...

, Menorca) of Spain, the islands of the Bahamas, Bermuda, Cuba, and many more.

As with all cave speleothems, the underwater speleothems in the Yucatán Peninsula are fragile. If a diver accidentally breaks off a stalactite

Stalactite

A stalactite , "to drip", and meaning "that which drips") is a type of speleothem that hangs from the ceiling of limestone caves. It is a type of dripstone...

from the ceiling or other speleothem formation, it will not reform as long as the cave is underwater so active cave conservation diving techniques are paramount.

In plan form, the Quintana Roo caves are extremely complex with anastomotic interconnected passages. When cave diving through the caves, the pathways then appear to have many offshoots and junctions, requiring careful navigation with permanent tees or the implementation of jumps in the guideline.

The beginning of the 1980s brought the first cave divers from the U.S. to the Yucatán Peninsula, Quintana Roo to explore cenotes such as Carwash, Naharon and Maya Blue, but also to central Mexico where resurgence rivers such as Rio Mante, sinkholes such as Zacaton were documented.

In the Yucatán, the 1980s ended with the discoveries of the Dos Ojos and Nohoch Nah Chich

Nohoch Nah Chich

Sistema Nohoch Nah Chich is an extensive water filled cave system connected with the Caribbean Sea via a coastal spring called a variety of names, including Casa Cenote for the restaurant located nearby, but also Cenote Manati, or Cenote Tankah...

cave systems which lead into a long ongoing competition of which exploration team had the longest underwater cave system in the world at the time, with both teams vying for first place.

The beginning of the 1990s led into the discovery of underwater caves such as Aereolito on the island of Cozumel

Cozumel

Cozumel is an island in the Caribbean Sea off the eastern coast of Mexico's Yucatan Peninsula, opposite Playa del Carmen, and close to the Yucatan Channel. Cozumel is one of the ten municipalities of the state of Quintana Roo...

, ultimately leading to the 5th biggest underwater cave in the world.

By the mid 1990s a push into the central Yucatán Peninsula by dedicated deep cave explorers discovered a large number of deep sinkholes, or pit cenotes, such as Sabak Ha, Utzil and deep caves such as Chacdzinikche, Dzibilchaltun, Karkirixche that have been explored and mapped. To this day these deep caves of the central Yucatán remain largely unexplored due to the sheer number of cenotes found in the State of Yucatán, as well as the depth involved that can be only tackled using technical diving techniques or rebreathers. In the end of the last millennium closed circuit rebreather (CCR) cave diving techniques were employed in order to explore these deep water filled caves.

By the end of the 1990s, "The Pit" in the Dos Ojos cave system located 5.8 km from the Caribbean coast had been discovered, and it is presently (2008) 119 m deep. At that time, technical diving and rebreather equipment and techniques became common place.

By the turn of the millennium the longest underwater cave system at that time, Ox Bel Ha was established by cave diving explorers whose combined efforts and information helped join segments of previously explored caves. The use of hand held GPS technology and aerial and satellite images for reconnaissance during exploration became common. New technology such as rebreathers and diver propulsion vehicles (DPVs) became available and were utilized for longer penetration dives. As of October 2010, Ox Bel Ha includes 182 km of underwater passage (See QRSS

Quintana Roo Speleological Survey

The Quintana Roo Speleological Survey is a special project of the National Speleological Society. It supports safe exploration, survey and cartography of the underwater and dry caves and cenotes of Quintana Roo, Mexico...

for current statistics).

Active exploration continues in the new millennium. Most cave diving exploration is now conducted on the basis of "mini projects" lasting 1 – 7 days, and occurring many times a year, and these may include daily commutes from home to jungle dive base camps located within 1 hour from road access.

Starting in 2006 a number of large previously explored and mapped cave systems have been connected utilizing sidemount cave diving techniques and many times no-mount cave diving techniques in order to pass through these tight cave passages, creating the largest connected underwater cave system on the planet, Sac Actun

Sac Actun

Sistema Sac Actun is an underwater cave system situated along the Caribbean coast of the Yucatán Peninsula with passages to the north and west of the village of Tulum. Exploration started from Gran Cenote west of Tulum...

, which presently has a length extent of 215 km (See QRSS

Quintana Roo Speleological Survey

for current statistics).

Many cave maps have been published by the Quintana Roo Speleological Survey (QRSS).

United Kingdom

UK requirements are generally that all people wishing to take up cave diving must be competent cavers before they start cave diving. This is primarily because most British cave dives are at the far end of dry caves. There are individuals that begin cave diving directly from the recreational diving

Recreational diving

Recreational diving or sport diving is a type of diving that uses SCUBA equipment for the purpose of leisure and enjoyment. In some diving circles, the term "recreational diving" is used in contradistinction to "technical diving", a more demanding aspect of the sport which requires greater levels...

, but they represent a minority in the UK, and represent only a few percent of the Cave Diving Group

Cave Diving Group

(CDG).

Australian cave diving and the CDAA

Australia has many spectacular water filled caves and sinkhole

Sinkhole

A sinkhole, also known as a sink, shake hole, swallow hole, swallet, doline or cenote, is a natural depression or hole in the Earth's surface caused by karst processes — the chemical dissolution of carbonate rocks or suffosion processes for example in sandstone...

s, but unlike the UK, most Australian cave divers come from a general ocean-diving background. The "air-clear" water of the sinkholes and caves can be found in the Mount Gambier

Mount Gambier, South Australia

Mount Gambier is the largest regional city in South Australia located approximately 450 kilometres south of the capital Adelaide and just 17 kilometres from the Victorian border....

area of south-eastern Australia

South Australia

South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...

. The first cave and sinkhole dives here took place in the very late 1950s, and until the mid 1980s divers generally used single diving cylinder

Diving cylinder

s and homemade torches, and reels

Distance line

, resulting in most of their explorations being limited.

A series of tragedies between 1969 and 1973 in which 11 divers drowned (including a triple and a quadruple fatality) in just four karst features - "Kilsbys Hole", "Piccaninnie Ponds", "Death Cave" and "The Shaft" - created much public comment and led to the formation of the Cave Divers Association of Australia (CDAA) Inc. in September 1973. As a consequence of the CDAA's assessment programs, divers are rated at various levels, and today they comprise Deep Cavern, Cave, and Advanced Cave. Five further deaths have occurred since 1974; two died at Piccaninnie Ponds in 1983, one person died at Kilsbys Hole in 2010, and two people died in separate incidents at Tank Cave in 2011 including noted cave diver Agnes Milowka

Agnes Milowka

Agnes Milowka was an Australian technical diver, underwater photographer, author, and cave explorer.She gained the international recognition for extending the cave systems across Australia and Florida, and as a public speaker and the author on subject of diving and maritime...

.

During the 1980s the Nullarbor Plain

Nullarbor Plain

The Nullarbor Plain is part of the area of flat, almost treeless, arid or semi-arid country of southern Australia, located on the Great Australian Bight coast with the Great Victoria Desert to its north. It is the world's largest single piece of limestone, and occupies an area of about...

was recognized as a major cave-diving area, with one cave, Cocklebiddy, being explored for more than 6 kilometers, involving the use of large sleds to which were attached numerous diving cylinders and other paraphernalia, and which were then laboriously pushed through the cave by the divers. In more recent years divers have been utilizing compact diver-towing powered scooters

Diver Propulsion Vehicle

A diver propulsion vehicle is an item of diving equipment used by scuba and rebreather divers to increase range underwater...

, but the dive is still technically extremely challenging. A number of other very significant caves have also been discovered during the past 10 years or so; the 10+ (Lineal) kilometre long Tank Cave near Mount Gambier, other very large features on the Nullarbor and adjacent Roe Plain as well as a number of specific sites elsewhere, and nowadays the cave diving community utilizes many techniques, equipment and standards from the U.S. and elsewhere.

The CDAA is one of a number of organisations responsible for the administration of cave diving certification in Australia. Mixed-gas and rebreather

Rebreather

technologies can now be used in many sites. All cave diving in the Mount Gambier area as well as at some New South Wales sites and the Nullarbor requires divers to be members of the CDAA, whether in the capacity of a visitor or a trained and assessed member.

Brazil

In Brazil there is cavern diving in Chapada da Diamantina, in Bahia

Bahia

Bahia is one of the 26 states of Brazil, and is located in the northeastern part of the country on the Atlantic coast. It is the fourth most populous Brazilian state after São Paulo, Minas Gerais and Rio de Janeiro, and the fifth-largest in size...

state; Bonito

Bonito

Bonito is a name given to various species of medium-sized, predatory fish in the Scombridae family. First, bonito most commonly refers to species in the genus Sarda, including the Atlantic bonito and the Pacific bonito ; second, in Japanese cuisine, bonito refers to the skipjack tuna , which, in...

, in Mato Grosso do Sul

Mato Grosso do Sul

Mato Grosso do Sul is one of the states of Brazil.Neighboring Brazilian states are Mato Grosso, Goiás, Minas Gerais, São Paulo and Paraná. It also borders the countries of Paraguay and Bolivia to the west. The economy of the state is largely based on agriculture and cattle-raising...

state; and Mariana

Mariana, Minas Gerais

Mariana is the oldest city in the state of Minas Gerais, Brazil. It is a touristic city, founded on July 16, 1696, and retains the characteristics of a baroque city, with its churches, buildings and museums.-Further reading:...

, where there is also cave diving (visiting Mina da Passagem), in Minas Gerais

Minas Gerais

Minas Gerais is one of the 26 states of Brazil, of which it is the second most populous, the third richest, and the fourth largest in area. Minas Gerais is the Brazilian state with the largest number of Presidents of Brazil, the current one, Dilma Rousseff, being one of them. The capital is the...

state. For cave diving in Mariana a cave diver certification will be required.

Sardinia Italy

In the north west of Sardinia

Sardinia

Sardinia is the second-largest island in the Mediterranean Sea . It is an autonomous region of Italy, and the nearest land masses are the French island of Corsica, the Italian Peninsula, Sicily, Tunisia and the Spanish Balearic Islands.The name Sardinia is from the pre-Roman noun *sard[],...

, close to Porto Conte bay, Alghero

Alghero

Alghero , is a town of about 44,000 inhabitants in Italy. It lies in the province of Sassari in northwestern Sardinia, next to the sea.-History:The area of today's Alghero has been settled since pre-historic times...

territory, there is the most important cave diving site in the Mediterranean Sea

Mediterranean Sea

The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...

. Thanks to the huge limestone cliffs of Capo Caccia and Punta Giglio there are more than 300 caves above and below water, with about 30 large, and many smaller, underwater sea caves. The Nereo Cave

Nereo Cave

The Nereo Cave is a huge underwater sea-cave situated on the north-west of Sardinia in the Coral riviera of Alghero, Italy. The name was given by the discovers in honour of the mythological figure Nereus, who is often billed as the Old Man of the Sea, father of the Nereids...

is the most important and it is considered also the largest in the Mediterranean Sea. On the east side of Sardinia there are many underwater cave systems starting from the Gennargentu

Gennargentu

Gennargentu is a large massif in central-southern Sardinia, Italy, encompassing the provinces of Nuoro and Ogliastra. It includes the highest peaks in the island, such as Punta La Marmora , Monte Spada , Punta Erba Irdes , Bruncu Spina and Punta Paulinu .The range forms part of the Gennargentu...

Mountains, with underwater rivers which arrive at the sea by different, lengthy routes. Here one of the deepest fresh water caves exits at more than 110 m (360.9 ft) depth.

Sources

"Skin Diver Killed in Submerged Cave", The New York Times
The New York Times
The New York Times is an American daily newspaper founded and continuously published in New York City since 1851. The New York Times has won 106 Pulitzer Prizes, the most of any news organization...

, May 16, 1955, Page 47.
Basic Cave Diving: A Blueprint for Survival, Sheck Exley
Sheck Exley
-Biography:Exley is widely regarded as one of the pioneers of cave diving, writing two major books on the subject: Basic Cave Diving: A Blueprint for Survival and Caverns Measureless to Man published by Cave Books, , and establishing many of the basic safety procedures used in cave and overhead...

1977.

External links

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