Floating plastic, endangered sea turtles, and successfully mating humpback whales--all are featured in this amiable account of an ecological Caribbean sailing tour by the former director of the Center for Marine Conservation. Ice covered the Potomac in Washington, D.C., when Frankel departed on his six-month journey in the winter of 1987, but the Center's 32-foot schooner nevertheless succeeded in transporting its mild-mannered ecological watchdog on a 5,000-mile combination pleasure cruise and firsthand survey of 22 Caribbean islands, including Cuba. Frankel's report, oddly casual considering the issues involved, offers ample proof that sea turtles and black coral continue to be actively sold, despite laws, in nearly every port town; that beaches are cluttered with plastic debris; and that mangrove trees--a rich habitat for marine life--are increasingly threatened by development. (On the plus side, Frankel watched whales sporting in a watery sanctuary and was surprised at the extent of park acreage on the islands.) Periodically rising above his preoccupations with hot showers and Caribbean ice cream, Frankel manages to make some cogent suggestions for environmental improvement: Since impoverished economies are unlikely to give up the income-producing sale of black coral and turtles, tourists should be educated not to buy them. Powerful developers need to be convinced that aesthetically pleasing mangroves and plastic-free oceans are in their own best interest. Sensitive coral and sea grass, hurt by cruise ships' heavy anchors, can be protected by using regulated moorings. Informative boxed insets abound, covering everything from the Sargasso Sea to coral reefs--as do cheerful descriptions of crew members' bouts of seasickness--but one wishes for a more in-depth, serious study from this amply qualified source.