An author familiar with both fiction and fact, Mr. del Rey now concentrates on the fantastically true mysteries of the sea in this companion volume to The Mysterious Earth (1960, p.J33). As vividly written, as carefully researched, this is an accurate description of underwater explorations, the elemental makeup of the sea, the enormous range of existent sea life, daring underwater exploits, myths and legends built up around the earth's waters, and man's possible dependence on the sustaining forces of the sea in the future. Readers who want more than incidental information are let in on countless secrets as they delve far beneath the surface.