Nautical Archaeology

In the first century A.D., two large Roman ships sank to the bottom of Lake Nemi, southwest of Rome. Rumored to be carrying treasure, and lying at the relatively shallow depth of 49-75.5 ft (15-23 m), they were not entirely forgotten. In 1446, at the request of a church official, the noted Italian architect and theorist Leon Battista Alberti (1404-1472), assisted by divers, attempted to tow one of the ships to shore but succeeded only in raising a large statue. In 1556, a diver wearing a primitive diving apparatus consisting of a wooden "hood" and crystal face plate visited the site. He returned with a description of the ships, claiming that the decks were paved with red brick. In the late nineteenth century, the antiquities dealer Eliseo Borghi began to remove objects from the vessel and sell them at high prices to the Italian government, but the government soon halted Borghi's financial venture. It was not until 1928 that the Italian dictator Benito Mussolini, intrigued by rumors of the buried treasure, decided to raise the ships by draining the lake, partially by means of an old Roman overflow tunnel. Four years later, the water level had been lowered more than 70 ft (229.5 m), and the ships were raised, cleaned, and moved to a museum. No "treasure" was found, but the ships themselves were a spectacular find: they contained heated baths, private cabins, and paved mosaic decks. Both ships were destroyed during World War II.

The first large-scale salvage of a shipwreck was carried out by the Greek Navy in 1900. In about 80 B.C., a Roman vessel carrying a cargo of Greek amphorae (twohandled storage jars) sank to a depth of 60 m (197 ft) near the island of Antikythera, between Crete and southern Greece. Divers worked under extremely dangerous conditions to excavate the wreck. Laboring in storm-tossed seas, and able to remain submerged for only five minutes at a time, the divers nevertheless brought up a number of valuable objects. These included a statute by the Greek sculptor Lycippus and an early astronomical computer.

The first systematic archaeological excavation of a shipwreck was carried out in 1952 under the direction of Jacques-Yves Cousteau and Frédéric Dumas. The French team excavated a Roman amphora carrier that had sunk in the second century B.C. at Grand Congloué, near Marseilles. To assist in surveying the wreck, they decided to employ underwater photographic equipment. They also used a method known as an "airlift " to bring the amphorae to the surface. In this method, unbroken amphorae were filled with air, causing them to rise to the top of the water. To clear off debris from the wreck, the team used a vacuum pump attached to the ship.

The photojournalist Peter Throckmorton and the archaeologist George Bass employed underwater photography and precise methods of surveyance to excavate the Gelidonya wreck off the coast of Turkey. In about 1200 B.C., a trade vessel loaded with more than a ton of metal hit rocks and sank to the bottom of the sea on its journey to Phoenicia (modern-day Syria, Lebanon, and Israel). Explorers worked at a depth of 90 ft (27 m). They pinpointed the location of each object before bringing it to the surface. Heavy objects were raised with a winch and borne to the surface by air bags.

In 1961-64, Bass led the first excavation to be conducted completely underwater. Divers explored a wreck located off the coast of Turkey. Not far from the island of Yassi Ada, a seventh-century Byzantine amphora carrier lay buried in the sand, its wooden structure partially devoured by teredos. Rescuers excavated the ship by using bicycle spokes to keep the fragile wood from breaking off and drifting away until their work could be completed. To give them a better picture of the site, they built a metal scaffold overhead, complete with 16-ft-high (5 m) photographic towers. The undamaged part of the ship was salvaged and completely reassembled on land.

All of the wrecks discussed above were excavated in the Mediterranean Sea. Many wrecks have been excavated in other parts of the world-for example, China. In 1973 a shipwreck was discovered off the coast of Quanzhou in east China. Its cargo contained pottery and fragrant wood. Dated to 1277, the ship is one of the earliest examples of Chinese nautical design. Examination of the wreck brought to light a new fact about Chinese ship construction. Chinese ships were not flat-bottomed, as formerly believed, but rather V-shaped, with a keel that tapered inward.