A history of menfish or divers. ""From the evolutionary point of view, every piece of diving equipment is an artificial organ which is formed not through cell mutation but by an act of intelligence."" Hass has been a manfish since his first oxygen-tank submersion in 1940. By 21 he was a famous author and photographer, supporting his underwater research with his popular productions (his documentary Adventure in the Red Sea won a first prize at the 1951 Venice film festival). He seems to have read absolutely everything about the sea, from Homer to Arthur C. Clarke, and has specialized in marine biology. Skeptical of fantastic sea-beasts, he admits that the sixteen-inch eye of a squid has been recovered from a whale's belly, and that sooner or later man is bound to meet one of the eighty-foot giants. Perhaps his most spellbinding chapter is on sharks, a predator not as black as it is painted. In fact, says Hass; sharks are shy and never attack humans unless the man is already bleeding or a fish has been speared nearby -- blood being the excitant. He foresees widespread use of the sea to meet demands of the coming population explosion on land and has drawn up manifestos for its protection from pollutants and exploitation. This book is indeed a thorough survey of our present knowledge of the oceans and their potential benefits.