The subtitle identifies the readership: For Fish Collectors/Treasure Divers/Photographers/Snorklers. The good-sized, clearly captioned, full-color photographs (one or two to each page) explain the high price. The authors are marine biologists and they keep to the fundamentals of the areas indicated by the subtitle. Their own enthusiasm keeps their writing fresh and they include the many details beginners need to know for each of the subjects presented. A chart of photographic data on exposures for each depth appears at the back of the book and includes information about color filters. Index. While the price may seem prohibitive for smaller collections, the highly visual approach recommends this as the sort of information that can be shared by adults and younger readers just beginning serious underwater exploration.