An over-all, and all over, survey of underwater exploration makes its start with earliest known examples of diving and apparatus and follows its history up to the present day, with the Bathyscaphe and aqua-lunging. It shows how equipment developed; how greater and greater depth was achieved; the beginning and current activities of the new breed of ""men-fish"". It goes on to chart the hows and wheres of treasure troves and covers the attempts to attain them; it checks salvaging operations, successful and otherwise; it does not neglect submarine photography, camera and TV, and the practical uses to which these may be put. There are further chapters on underwater clubs, hunters, archeologists; the prospects of tunnels under the Channel and the Mediterranean and of striking oil. Excerpts from the records of active participants add to this round-up which should add a few fine points to an already well steeped area.