Ships and the sea were an omnipresent theme of Greek and Roman art and life. Shipwreck was a well-recognized risk, and an essential ingredient of ‘lost and found’ stories in novels and comedies. Conversely, safe arrival in harbour, the successful end of a journey, was a frequent motif, especially of Roman art. These ideas were obviously underpinned by economic facts: the need for metals, the sea-girt nature of Greece, Rome’s central position in the Mediterranean, and the constant threat of food shortage in the cities of the Mediterranean world generally, necessarily involved transport and trade by sea.
Into this scene has stepped, still less than 50 years old, a new character, namely underwater archaeology. Since 1945, over 1000 ancient and medieval shipwrecks have been reported in the Mediterranean, and the roll continues to grow at an unslackened pace. This rapid increase in archaeological resource has been due, of course, mainly to the widespread use of compressed-air diving gear for sport, so that most of the known wreck sites lie in inshore waters, and in popular diving areas. However, recent developments in offshore position-fixing and in underwater communications and robotics have made it possible to explore much deeper sites; the deepest so far to have been surveyed under archaeological direction (by A.M. McCann) is a late Roman wreck at 800 m deep between Sicily and Sardinia.