The potential richness of the sea for salvage or accidental finding of sunken valuables was recognized from earliest times, but the possibility of defining meaningful groups of wrecked material or of interpreting submerged sites scarcely predates the widespread adoption of underwater breathing-apparatus in the 20th cent. Standard apparatus, supplied with compressed air from the surface, as used by sponge divers, enabled the discovery and partial excavation of rich 1st-cent. bce cargoes at Antikythera (1900–1) and Mahdia (1908–13), but the unwieldy equipment, reliance on untrained working divers, and exclusion of archaeological direction from involvement under water remained serious limitations on progress. Self-contained breathing-apparatus (the aqualung) came into widespread use after 1945, and resulted in the growth of diving for sport and pleasure; many ancient wrecks were discovered, especially in southern France, and the importance of this resource was recognized by F. Benoit. However, he did not direct operations under water, and his main underwater project, the excavation at the islet of Le Grand Congloué (1952–7), has subsequently been shown to have confused two superimposed Roman wrecks.Less