Come put on your swim mask and fins and compressed-air tank and dive with us through the looking glass into the sea."" With this invitation, we are carefully submerged to the depths for a peek at the great watery world beneath and a subjective accounting of the various techniques of diving and the development of equipment for this purpose. From here we pass wide-eyed from the Mediterranean, to the shores of the North Atlantic, to rivers and bays, down to the Sacred Well of the Maya civilization in order to view the wondrous underwater archaeological excavations of past and present times. The discoveries of famous shipwrecks, sunken cities, Spanish galleons, water-logged gold and valuable amphora pass before us in fascinating array. The thrills and perils of diving are described with astute accuracy and the quests of underwater pioneers both historical and modern, may challenge the would-be diver, but will surely interest the armchair variety.