From the authors of "The Field Guide to Bigfoot, Yeti and Other Mystery Primates Worldwide", this book tackles the various sea serpents, lake monsters and other aquatic cryptids in the same manner. It's not exactly an in-depth scientific survey, but it is a pretty good introduction to the phenomena, and it does try to cover a vast array of hypothetical species. We begin with a history of the sea serpent, going through important historical sightings, early studies of sea serpents, the discovery of the giant squid, and Heuvelmans attempted categorization. In these sections the book reads pretty much as a general history of Cryptozoology, so most readers will probably be familar with the material.
The real meat of the book comes in from the "species profiles", in which Coleman and Huyghes showcase the different cryptids they came up with in their system. Some come from Heuvelmans' studies (with a new look at the "supper otter") while others are entirely new. Each write-up includes an illustration, maps, an overview of the creature and it's habitats, range and behavior, and a few brief sightings. All in all, over a dozen species are covered. We are presented with the familar "classic sea serpent", the "water horse" (maned, long necked seals according to the authors), Heuvelman's "sea centipede" (a multi-finned whale), marine crocodiles and giant sharks, sea turtles and octopi. More exotic sea creatures mentioned included the Trinty Alps giant salamander, Mokole-Mbembe (a surviving dinosaur said to dwell in the Congo), the Buru (a possibly extinct monitor lizard from the Himalayas), surviving populations of Steller's sea cows, a giant beaver seen in Utah's Salt Lake and unidentified species of manta rays and whales.
Obviously some cryptids are more believable than others, but all are given a good amount of space, along with the authors attempts at finding a scientific explanation for them. In the back of the book, we are given some interesting material such as an essay about the latitudes in which lake monsters are found, some accounts about "globsters" and other unidentified carcasses that have washed ashore, and a list of locations around the world in which sea, lake and river monsters can be sighted. On small comment is that several of the creatures mentioned in this list aren't mentioned at all in the text, but thats a small gripe.
Ultimately, this is a fun little book, especially for the lay reader who wants to know whether or not there is any possibility of discovering sea monsters in this day and age. Obviously some of the claims need to be taken with a grain of salt, but this book still provides a fun and interesting read. However, for the reader with a serious interest in cryptozoology, this book isn't going to replace Heuvelmans' monumental "In the Wake of Sea Serpents". Its still worth including in your personal library, but it's not the be-all, end-all word on marine cryptids.