Of these two handsome volumes, the Ocean Wave deserves special attention for pointing out the factors such as temperature, nutrient content, vegetation and marine life, which makes the superficially uniform seas a diverse web of interrelated environments. Within this context, Silverberg examines the constituents of plankton -- concentrating on the most peculiar and widely known forms (sargasso weed, red tide, etc.), and includes an amusing chapter on the reactions of Heyerdahl's crew, oceanographer Alister Hardy and others who have attempted to survive on a plankton diet. The tour of the Tide Pool is more purely descriptive, but includes a good explanation of tidal phenomena and introduces many varieties of animals and the most common forms of vegetation. Both books end with strongly worded warnings on the dangers of pollution, though unfortunately relying on some of the same examples -- the Torrey Canyon disaster and Heyerdahl's observations of solidified chunks of oil in mid-ocean. Silverberg teaches ecology instead of preaching it (his skeptical examination of the promise of unlimited food from the sea is particularly welcome), and Bob Hines' graceful and accurate black and white drawings are an accomplishment in themselves.