First published in 1992, this guide has been significantly expanded in a new 3rd edition. The popular, user-friendly field guide, covering all major groups of marine invertebrates encountered by divers on coral reefs and adjacent habitats, has grown to include 900 species beautifully documented with more than 1200 underwater photographs -- nearly doubling the total in the previous editions. Les Wilk has joined Paul Humann and Ned DeLoach authoring the comprehensive new edition.