Nemi ships
The Nemi Ships were 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 built by the Roman emperor Caligula
Caligula , also known as Gaius, was Roman Emperor from 37 AD to 41 AD. Caligula was a member of the house of rulers conventionally known as the Julio-Claudian dynasty. Caligula's father Germanicus, the nephew and adopted son of Emperor Tiberius, was a very successful general and one of Rome's most...

 in the 1st century AD at Lake Nemi
Lake Nemi
Lake Nemi is a small circular volcanic lake in the Lazio region of Italy south of Rome, taking its name from Nemi, the largest town in the area, that overlooks it from a height.-Archaeology and history:The lake is most famous for its sunken Roman ships...

. Although the purpose of the ships is only speculated on, the larger ship was essentially an elaborate floating palace, which contained quantities of marble, mosaic floors, heating and plumbing such as baths among its amenities. Both ships featured technology long thought to be recent inventions. It has been stated that the emperor was influenced by the lavish lifestyles of the Hellenistic rulers of Syracuse
Syracuse, Italy
Syracuse is a historic city in Sicily, the capital of the province of Syracuse. The city is notable for its rich Greek history, culture, amphitheatres, architecture, and as the birthplace of the preeminent mathematician and engineer Archimedes. This 2,700-year-old city played a key role in...

 and Ptolemaic Egypt
Ptolemaic Egypt
Ptolemaic Egypt began when Ptolemy I Soter invaded Egypt and declared himself Pharaoh of Egypt in 305 BC and ended with the death of queen Cleopatra VII of Egypt and the Roman conquest in 30 BC. The Ptolemaic Kingdom was a powerful Hellenistic state, extending from southern Syria in the east, to...



Lake Nemi is a small circular volcanic lake in the Lazio region of Italy 30 km (18.6 mi) south of Rome. It has a surface of 1.67 km² (0.644790604849534 sq mi) and a maximum depth of 33 metres (108.3 ft).

There is considerable speculation regarding why the emperor Caligula chose to build two large ships on such a small lake. From the size of the ships it was long held that they were pleasure barges, though, as the lake was sacred, no ship could sail on it under Roman law (Pliny the Younger
Pliny the Younger
Gaius Plinius Caecilius Secundus, born Gaius Caecilius or Gaius Caecilius Cilo , better known as Pliny the Younger, was a lawyer, author, and magistrate of Ancient Rome. Pliny's uncle, Pliny the Elder, helped raise and educate him...

, Litterae VIII-20) implying a religious exemption.

Caligula particularly favoured the Egyptian Isis cult
Isis or in original more likely Aset is a goddess in Ancient Egyptian religious beliefs, whose worship spread throughout the Greco-Roman world. She was worshipped as the ideal mother and wife as well as the matron of nature and magic...

 which he had established in Rome and also supported that of Diana Nemorensis
Diana (mythology)
In Roman mythology, Diana was the goddess of the hunt and moon and birthing, being associated with wild animals and woodland, and having the power to talk to and control animals. She was equated with the Greek goddess Artemis, though she had an independent origin in Italy...

 whom, in the Roman tradition of syncretism
Syncretism is the combining of different beliefs, often while melding practices of various schools of thought. The term means "combining", but see below for the origin of the word...

, he likely viewed as an aspect of Isis.

Situated on opposite sides of the lake and atop the crater walls, are the towns of Genzano
Genzano di Roma
Genzano di Roma is a town and comune in the province of Rome, in the Lazio region of central Italy. It is one of the Castelli Romani, at a distance of 29 km from Rome, on the Alban Hills.-History:The origin of the name Genzano is still disputed...

 which was dedicated by the Romans to the goddess Cynthia, a cult associated with that of Diana Nemorensis and Nemi
Nemi is a town and comune in the province of Rome , in the Alban Hills overlooking Lake Nemi, a volcanic crater lake. It is 6 km NW of Velletri and about 30 km southeast of Rome....

, which did not exist in Roman times. The name Nemi derives from the Latin nemus Aricinum (grove of Ariccia), Ariccia
Ariccia is a town and comune in the Province of Rome, central Italy. It is in the Alban Hills of the Lazio region and could be considered an extension of Rome's southeastern suburbs...

 being an important nearby town associated with the worship of Diana and the god Virbius. Located at Nemi are the ruins of an ancient temple dedicated to Diana, which was connected by the Via Virbia to the Via Appia
Appian Way
The Appian Way was one of the earliest and strategically most important Roman roads of the ancient republic. It connected Rome to Brindisi, Apulia, in southeast Italy...

 (the Roman road between Rome and Brindisi
Brindisi is a city in the Apulia region of Italy, the capital of the province of Brindisi, off the coast of the Adriatic Sea.Historically, the city has played an important role in commerce and culture, due to its position on the Italian Peninsula and its natural port on the Adriatic Sea. The city...


During the Roman empire the area around Genzano was used by wealthy Roman citizens for its clean air, uncontaminated water and cooler temperatures during the hot summer months. The lake has its own microclimate
A microclimate is a local atmospheric zone where the climate differs from the surrounding area. The term may refer to areas as small as a few square feet or as large as many square miles...

 and is protected from wind by the crater walls. Goethe
Johann Wolfgang von Goethe
Johann Wolfgang von Goethe was a German writer, pictorial artist, biologist, theoretical physicist, and polymath. He is considered the supreme genius of modern German literature. His works span the fields of poetry, drama, prose, philosophy, and science. His Faust has been called the greatest long...

, Lord Byron
George Gordon Byron, 6th Baron Byron
George Gordon Byron, 6th Baron Byron, later George Gordon Noel, 6th Baron Byron, FRS , commonly known simply as Lord Byron, was a British poet and a leading figure in the Romantic movement...

 and Gounod
Charles Gounod
Charles-François Gounod was a French composer, known for his Ave Maria as well as his operas Faust and Roméo et Juliette.-Biography:...

 all lived in Nemi and seen the magical reflection of the Moon seen in the center of the lake during summer. This phenomenon is the source of the Roman name for the lake, Speculum Dianae (Diana's Mirror
Diana Nemorensis
Diana Nemorensis, "Diana of Nemi" also known as “Diana of the Wood”, was an Italic form of the goddess who became Hellenised during the fourth century BCE and conflated with Artemis. Her sanctuary was to be found on the northern shore of Lake Nemi beneath the cliffs of the modern city Nemi...



Local fishermen had always been aware of the existence of the wrecks, and had explored them and removed small artifacts. In 1446, Cardinal Prospero Colonna
Prospero Colonna (cardinal)
Prospero Colonna was a cardinal-nephew of Pope Martin V , whose election ended the Western Schism. Colonna was excommunicated for a period due to his rebellion against Martin V's successor, Pope Eugene IV, becoming one of the few excommunicated cardinals...

 and Leon Battista Alberti followed up on the stories regarding the remains and discovered them lying at a depth of 18.3 metres (60 ft), which was too deep for effective salvage. They caused significant damage to the ships by using ropes with hooks to tear planks from them. Alberti learned little more than the type of wood and that it was covered in lead sheathing. In 1535, Francesco De Marchi dove on the wreck using a 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....

. From material recovered he added the knowledge that mortise and tenon
Mortise and tenon
The mortise and tenon joint has been used for thousands of years by woodworkers around the world to join pieces of wood, mainly when the adjoining pieces connect at an angle of 90°. In its basic form it is both simple and strong. Although there are many joint variations, the basic mortise and tenon...

 joints had been used in their construction. Despite the successful salvage of entire structures and parts, there was no academic interest in the ships so no further research was performed and the objects recovered were lost and their fate remains unknown.

By 1827, interest had revived and it had become a widespread belief that earlier material recovered had either been part of a temple to Diana or was from the villa of Caesar cited by Suetonius
Gaius Suetonius Tranquillus, commonly known as Suetonius , was a Roman historian belonging to the equestrian order in the early Imperial era....

. Annesio Fusconi built a floating platform to recover the wrecks but was unsuccessful.

In 1895, with the support of the Ministry of Education, Eliseo Borghi began a systematic study of the wreck site and discovered the site contained two wrecks instead of the one expected. Among the material Borghi recovered was the bronze tiller
A tiller or till is a lever attached to a rudder post or rudder stock of a boat that provides leverage for the helmsman to turn the rudder...

 head of one of the rudder
A rudder is a device used to steer a ship, boat, submarine, hovercraft, aircraft or other conveyance that moves through a medium . On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane...

s and many bronze heads of wild animals. Felice Barnabei, director general of the Dept of Antiquity and Fine Art submitted a report requesting the recovery cease due to the "devastation of the two wrecks." An engineer from the Italian Navy
Marina Militare
The Italian Navy is the navy of the Italian Republic. It is one of the four branches of military forces of Italy; formed in 1946, from what remained of the Regia Marina . As of 2008, the Italian Navy had 35,200 active personnel with 180 commissioned ships, 19 Floating Docks, and 123 aircraft...

 surveyed the site to determine the feasibility of recovering the two ships intact and concluded that the only viable way was to partially drain the lake.

In 1927, the Italian dictator Benito Mussolini
Benito Mussolini
Benito Amilcare Andrea Mussolini was an Italian politician who led the National Fascist Party and is credited with being one of the key figures in the creation of Fascism....

 ordered Guido Ucelli to drain the lake and recover the ships. With the help of the navy, army, industry, and private individuals, an ancient Roman underground water conduit linking the lake to farms outside the crater was reactivated. After connecting the conduit to a floating pumping platform, on October 20, 1928, the lake level began dropping. By March 28, 1929, the water level had dropped 5 metres (16.4 ft), and the first ship (prima nave) broke the surface. By June 10, 1931, the prima nave had been recovered and the second ship (seconda nave) was exposed. By this time the water level had dropped more than 20 metres (65.6 ft) with over 40 million cubic meters of water removed. As a result of the weight reduction, on August 21, 1931, 500,000 cubic meters of mud erupted from the underlying strata causing 30 hectares (74.1 acre) of the lake floor to subside. Work ceased and, while the risks of continuing the project were debated, the lake began refilling. As the seconda nave had already partially dried out the submersion caused considerable damage. On November 10, 1931, the Minister of Public Works ordered the project and all research abandoned.

On February 19, 1932, the Navy Ministry, which had been a partner in the recovery, petitioned the Prime Minister to resume the project. Joining with the Ministry of Education they received permission to take over responsibility and pumping to drain the lake recommenced on March 28. Due to technical problems the seconda nave could not be recovered until October 1932. A purpose built museum constructed over both ships was inaugurated in January 1936.


Both vessels were constructed using the Vitruvian method, a shell first building technique used by the Romans.
  • Step 1: construction of the profile.
  • Step 2: construction of the 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...

     and the flat bottom up to the second order of cincti, in two phases.
  • Step 3: construction of the shell up to the third wale (topgallant bulwarks).
  • Step 4: Insertion of the ribs, first those with trabes (crossbeam bracing) and then those without.

The hull had been sheathed in three layers of lead sheeting to protect the timbers from shipworm
Shipworms are not worms at all, but rather a group of unusual saltwater clams with very small shells, notorious for boring into wooden structures that are immersed in sea water, such as piers, docks and wooden ships...

s; as there are none in fresh water lakes, this design feature was not only useless but costly. It is evidence that the ships hulls were constructed following standardized Roman shipbuilding techniques rather than being purpose built. The topside timbers were protected by paint and tarred wool with many surfaces decorated with marble
Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite.Geologists use the term "marble" to refer to metamorphosed limestone; however stonemasons use the term more broadly to encompass unmetamorphosed limestone.Marble is commonly used for...

, mosaic
Mosaic is the art of creating images with an assemblage of small pieces of colored glass, stone, or other materials. It may be a technique of decorative art, an aspect of interior decoration, or of cultural and spiritual significance as in a cathedral...

s and gilded copper roof tiles. There was a lack of coordination between the structure of the hull and that of the superstructure
A superstructure is an upward extension of an existing structure above a baseline. This term is applied to various kinds of physical structures such as buildings, bridges, or ships...

s, which suggests that naval architects designed the hulls, while civil architects then designed the superstructure to use the space available after the hulls were completed. After their recovery, the ships hulls were found to be completely empty and unadorned.

They were steered using 11.3 metres (37.1 ft) long quarter oars, with the Seconda nave equipped with four, two off each quarter and two from the shoulders while the Prima Nave was equipped with two. Similar pairs of steering leeboards appear frequently in early 2nd century depictions of ships.

The Seconda nave was almost certainly powered by oars, as structural supports for the rowing positions protrude along the sides of the hull. The Prima nave had no visible means of propulsion so was likely towed to the center of the lake when in use.

A lead pipe found on one of the wrecks had Property of Gaius Caesar Augustus Germanicus stamped on it while many tiles had dates of manufacture. Together it leaves little doubt as to when the ships were built or for whom.

One year after being launched, the ships were stripped of precious objects, ballasted and then intentionally sunk following the assassination of Caligula.

Prima nave

The first ship recovered was 70 metres (229.7 ft) long with a beam (width) of 20 metres (65.6 ft).

The hull was divided into three "active" or main sections. The general shape of the hull appears wider at the stern
The stern is the rear or aft-most part of a ship or boat, technically defined as the area built up over the sternpost, extending upwards from the counter rail to the taffrail. The stern lies opposite of the bow, the foremost part of a ship. Originally, the term only referred to the aft port section...

 and thinner at the bow
Bow (ship)
The bow is a nautical term that refers to the forward part of the hull of a ship or boat, the point that is most forward when the vessel is underway. Both of the adjectives fore and forward mean towards the bow...

, in fact, the main section is not amidships but is displaced towards the stern. The superstructures appear to have been made of two main blocks of two buildings each, connected by stairs and corridors, built on raised parts of the deck at either end. This distribution gives the ship a discontinuous look and has no similarity to any other ancient construction.

Seconda nave

The second ship recovered was the larger at 73 metres (239.5 ft) in length and with a beam of 24 metres (78.7 ft).

The superstructure appears to have been made with a main section amidships, a heavy building at the stern and a smaller one at the prow. Although nothing remains of the stern and prow buildings their existence is indicated by the shorter spacing of the decks supporting cross beams and distribution of ballast. The arrangement of the Seconda nave superstructures is comparable to that of the shrines depicted on an Isian lamp held by the Museum of Ostia
Ostia (quarter of Rome)
Ostia is a large neighbourhood in the XIII Municipio of the comune of Rome, Italy. Ostia is also the only municipio or district of Rome on the Tyrrhenian Sea and many Romans spend the summer holidays there. Sometimes it is confused with Ostia Antica, an archaeological area, that is nearby...

. If not coincidental, this is further evidence of Isis worship rather than Diana.


The discovery proved that the Romans were capable of building large ships. Before the recovery of the Nemi ships, scholars often ridiculed the idea that the Romans were capable of building a ship as big as some ancient sources reported the Roman grain carriers were.

For centuries large numbers of lead bars have been found on the Mediterranean
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...

 seabed, and there was debate over whether they were anchor
An anchor is a device, normally made of metal, that is used to connect a vessel to the bed of a body of water to prevent the vessel from drifting due to wind or current. The word derives from Latin ancora, which itself comes from the Greek ἄγκυρα .Anchors can either be temporary or permanent...

 stocks or not. It was argued by some that iron tipped wooden anchors secured by ropes were not heavy enough to be effective so they had to have metal stocks and there was considerable academic controversy over the issue. The Nemi ships, constructed during the transition period when iron anchors were replacing wooden ones, were the first Roman wrecks found to have intact anchors, and confirmed that the lead bars were indeed anchor stocks. Two types of anchor were found, one of oak with iron-tipped flukes and a stock of lead while the other was of iron with a folding timber stock that closely matched the design of the Admiralty pattern anchor re-invented in 1841. In the 1960s, a similar anchor was found in Pompeii
The city of Pompeii is a partially buried Roman town-city near modern Naples in the Italian region of Campania, in the territory of the comune of Pompei. Along with Herculaneum, Pompeii was destroyed and completely buried during a long catastrophic eruption of the volcano Mount Vesuvius spanning...

 and in 1974 another was found buried near Aberdarewllyn in Gwynedd
Gwynedd is a county in north-west Wales, named after the old Kingdom of Gwynedd. Although the second biggest in terms of geographical area, it is also one of the most sparsely populated...

, Wales. These further discoveries confirmed that these technologically advanced anchors were a standard Roman design.

Both ships had several hand operated bilge pump
Bilge pump
A bilge pump is a water pump used to remove bilge water. Since fuel can be present in the bilge, electric bilge pumps are designed to not cause sparks. Electric bilge pumps are often fitted with float switches which turn on the pump when the bilge fills to a set level. Since bilge pumps can fail,...

s that worked like a modern bucket dredge, the oldest example of this type of bilge pump ever found. The pumps were also operated by what may have been the oldest crank handles
Crank (mechanism)
A crank is an arm attached at right angles to a rotating shaft by which reciprocating motion is imparted to or received from the shaft. It is used to change circular into reciprocating motion, or reciprocating into circular motion. The arm may be a bent portion of the shaft, or a separate arm...

 yet discovered; the reconstruction of the cranked pump which was assembled from fragments, including a wooden disk and an eccentric peg, has been dismissed as "archaeological fantasy".

Piston pumps
A piston is a component of reciprocating engines, reciprocating pumps, gas compressors and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from...

 (ctesibica machina: Vitruvius
Marcus Vitruvius Pollio was a Roman writer, architect and engineer, active in the 1st century BC. He is best known as the author of the multi-volume work De Architectura ....

 X.4?7) supplied the two ships with hot and cold running water via lead pipes. The hot water supplied baths while the cold operated fountains and supplied drinking water. This plumbing technology was later lost and only re-discovered in the Middle Ages
Middle Ages
The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...


Each ship contained a rotating statue platform. One platform was mounted on caged bronze balls and is the earliest example of the thrust ball bearing
Ball bearing
A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this by using at least two races to contain the balls and transmit...

 previously believed to have been first envisioned by Leonardo Da Vinci
Leonardo da Vinci
Leonardo di ser Piero da Vinci was an Italian Renaissance polymath: painter, sculptor, architect, musician, scientist, mathematician, engineer, inventor, anatomist, geologist, cartographer, botanist and writer whose genius, perhaps more than that of any other figure, epitomized the Renaissance...

 but only developed much later. Previous Roman ball bearing finds (used for water wheel axles in thermal baths) had a lenticular
Lens (geometry)
In geometry, a lens is a biconvex shape comprising two circular arcs, joined at their endpoints. If the arcs have equal radii, it is called a symmetric lens.A concave-convex shape is called a lune...

 shape. The second platform was almost identical in design but used cylindrical bearings. Although consensus is that the platforms were meant for displaying statues, it has also been suggested that they may have been platforms for deck cranes used to load supplies.


The ships were destroyed by fire in World War II
Italian Campaign (World War II)
The Italian Campaign of World War II was the name of Allied operations in and around Italy, from 1943 to the end of the war in Europe. Joint Allied Forces Headquarters AFHQ was operationally responsible for all Allied land forces in the Mediterranean theatre, and it planned and commanded the...

 on the night of May 31, 1944. There are conflicting views on which side was responsible for the destruction:

At that time, Allied forces were pursuing the retreating German army northward through the Alban Hills toward Rome. On May 28, a German artillery post was established within 400 feet (121.9 m) of the museum … An official report filed in Rome later that year described the tragedy as a willful act on the part of the German soldiers. A German editorial blamed the destruction on American artillery fire. The true story of what happened that night will probably never be known.

Only the bronzes, a few charred timbers and some material stored in Rome survived the fire. Due to the destruction, research effectively stopped until the 1980s.

Project Diana

Photographs, the drawings made for the Italian Navy survey and those made by the archaeologist G. Gatti survived, allowing reconstructions to be made of the two ships.

The Association Dianae Lacus (lake of Diana) was founded in 1995 to preserve the cultural and history of the Nemi Lake area and initiated Project Diana, which involves constructing a full size replica of the Roman prima nave (first ship) of Lake Nemi. As there is no record of the shape and size of the buildings and temples built on the deck the replica would be constructed to deck level only and when completed will be moored on the lake in front of the museum.

On July 18, 1998, the town council of Nemi voted to fund the construction of the forward section and work commenced in the Torre del Greco
Torre del Greco
-Main sights:*Roman archaeological remains, including the so-called "Villa Sora" , probably a property of the Flavians.*Monastery of the Zoccolanti, with a cloister housing 28 frescoed panels depicting the life of St...

 shipyards. This section was completed in 2001 with the section transported to the Nemi museum where the rest of the vessel would be constructed. The estimated final cost of the reconstruction is 7.2 million Euros (US$10.7 million). On November 15, 2003, Assimpresa, the second largest confederation of employers and businesses in Italy, announced it would sponsor the project by supplying all the timber required. No press releases have been made since 2004 and the Dianae Lacus website has closed.

See also

  • Caligula's Giant Ship
    Caligula's Giant Ship
    Caligula's "Giant Ship", also known as the 'round ship', was a very large barge whose ruins were found during the construction of Rome's Leonardo da Vinci International Airport in Fiumicino, Italy...

  • Syracusia
    Syracusia was a ancient Greek ship sometimes claimed to be the largest transport ship of antiquity. It only sailed once, from Syracuse in Sicily to Alexandria in the Ptolemaic Kingdom.-General characteristics:...

  • Glossary of nautical terms
    Glossary of nautical terms
    This is a glossary of nautical terms; some remain current, many date from the 17th-19th century. See also Wiktionary's nautical terms, :Category:Nautical terms, and Nautical metaphors in English.- A :...

  • List of world's largest wooden ships
  • Roman Navy
    Roman Navy
    The Roman Navy comprised the naval forces of the Ancient Roman state. Although the navy was instrumental in the Roman conquest of the Mediterranean basin, it never enjoyed the prestige of the Roman legions...

External links

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