We're still in the Stone Age in our exploitation of the sea,"" says scuba-diver Gott, referring to the animal, vegetable, and mineral wealth of the oceans. He's an amateur turned pro and runs his own skin-diving school in New York. A pro is a diver with special skills, largely mechanical, who knows how to weld, build, repair, or recover equipment for underwater figs or pipelines. Gott's experiences range from New York's East River to Vietnam, the Gulf of Mexico, the Caribbean, the Mediterranean, and the West Coast; and by now he considers himself literally an amphibian, a man truly at home in two worlds. He describes the various dangers of his jobs--the bends, panic, sharks--and keeps the reader entertained, even eager to try for a lobster or scungilli (edible squid). His best moments focus on exploring sunken vessels, some of them over two thousand years old. He explains in detail how to preserve the different metals and materials you may find, and how to photograph your underwater subjects to best advantage. Time-passing and informative but with no real hook.