I purchased this book because of the rather gushing reviews on Amazon and elsewhere. Unfortunately I didn't find it as good as some other buyers, in roughly ascending order, here's why.
It's quite an unattractive book, not nicely laid out and the illustrations are all black and white, not a problem if that was the only negative, but..
Although there's quite a bit of information in here, there's nothing that isn't covered by, and presented better in, the PADI "Open Water" and "Adventures in Diving" Manuals. The book is at about the level of an Advanced Open Water Diver, no more. I have no vested interest in PADI either.
Equipment is reviewed but prices are in dollars, it's cheaper in the US too, so not completely relevant. There's a bit about the ocean, haloclines, thermoclines etc. A weather section, a marine biology section, and a medical section that will put you off ever putting your head underwater. (The resolution is always "telephone DAN" anyway). It's trying to be a cover-all type of book, not a bad thing but it comes across as more pedantic than comprehensive.
There are 32 pages about diving in the United states, the rest of the world gets 9.
Some extremely useful info for (Americans) planning international trips is included, like "get a passport" (really). The perennial worry on every (American) diver's mind is also addressed in the 2 page section "Can your dive buddy sue you?"
The whole dive culture that comes across from this book seems to be at odds with that of Europe and some of the common underwater signals are not in there or are just wrong, which makes one doubt the author's diving experience. My internal warning bells ring when things like the author's personal OPINION on the use of a dry suit as buoyancy compensation, or not, is presented as FACT, whereas the dive community remains split on this issue.
There's also a Viz comic type of top tip about screwing a clip onto a weight, so that you can simply hang it off your belt / BCD if you should ever find yourself too buoyant. Which might sound logical to a non diver, but I can guarantee you, that any proper diver witnessing this would relish telling the tale in the pub for years to come, what a laugh will be had!
I'm sorry to be so negative about this book, which has obviously had quite a bit of effort put into it, but it doesn't really work. Perhaps if your considering taking up diving, and your an avid reader, it would make a great primer. As a certified diver, it isn't even a decent aide-memoire.