Ancona visits four major aquariums--in Boston, Baltimore, Monterey Bay, and N.Y.C.--photographing and describing buildings, special exhibits, curators, and inhabitants. The color photos are plentiful (there are 89), but many are too small and dark to be truly captivating, while the topical approach makes it difficult to get a sense of each facility's unique character. Some photos do enthrall--a caretaker stroking an octopus so that it will accept food from her, or a diver hand-feeding beluga whales. Scientific names are included, but no information on size. The need for conservation is emphasized. Attractive, but not outstanding. List of 21 US aquariums; index.