AbstractThe recent development of efficient free-diving apparatus has made possible underwater exploration for both sport and science. Human and cultural remains underwater are being extensively exploited. Although the term “underwater archaeology” is frequently applied to such activities, most are at the best only underwater salvage. Archaeological remains in lakes, springs, rivers, or the sea have considerable to offer. Perhaps their greatest value is the more complete condition of such artifacts in contrast to similar remains on land. However, they often suffer from decomposition, impregnation with minerals, or incrustation by algae or corals. Although context and sequential (or stratigraphic) position are not so easily found or recognized as on land, they are present in many cases. Any body of water is a possible site of study, but in practice, areas of potential importance are limited by location, depth, visibility, and bottom factors. There are four major types of underwater archaeological sites: (1) discarded refuse and “lost” material; (2) submerged sites of former human occupation; (3) shrines or places of offerings; and (4) shipwrecks.