The importance of biodiversity to planetary health and even human survival is now undisputed, yet little information exists about the importance of marine biodiversity. The world's oceans are exploited and used as dumping grounds with disastrous consequences for marine ecosystems and global biodiversity generally. This updated and revised edition offers a look at the condition of our oceans and provides an accessible explanation of marine biological diversity and the threats facing it. All varieties of marine ecosystems are discussed and practical, workable suggestions are provided for their protection. The book is intended as a tool for environmentalists, policymakers and all those concerned with the conservation of our marine environments.