The marine-archaeologist author of The Cave Divers (1976) and They Found Treasure (1977) guides the reader back, yet again, to famous wrecks like the Swedish man-of-war Vasa (raised intact from the Baltic mud after 300 years), the Spanish treasure galleon Atocha (which has already yielded $2 million in gold and silver), and the sunken hulk of the Civil War Monitor--whose remains may be so fragile, says Burgess, that she has to be lifted in situ (i.e., with an acre of sediment) and preserved in a kind of vast aquarium. Also somewhat novel--and tantalizing--is Burgess' talk about underwater digs 12,000 years old. Ice Age mastodon bones, he notes, were found more than 180 miles off the New England coast in what must once have been a dry environment; and skin divers have come up with human remains--possibly the oldest ever recovered in the western hemisphere--in Florida's numerous water-filled caverns. So, Burgess speculates, the deep natural reservoirs formed by Florida's crystal springs may hold clues to Man's origins. Nowhere, though, does he mention the ghostly vistas offered by WW II Pacific battlegrounds, where hundreds of Japanese ships and planes lie entombed. Familiar ground for seasoned treasure buffs, but as good a starting place as any for novices.