"Coral reefs declined worldwide during the 1980s and 1990s, making them perhaps the most endangered marine ecosystem on Earth. This realization spurred John W. Tunnell Jr. and others to write a comprehensive book that would raise awareness of coral reefs and their plight. Tunnell admits his personal stake in the matter: He has been diving in the waters off Veracruz, Mexico, for thirty years and has had, as he puts it, both the good fortune of seeing...