Although he has some points, I disagree with the previous reviewer's harsh one-star assessment of this text. The second edition of this text dates to 1995, and as such can't be completely dismissed (other than some details which I will cover below).
I have been diving for 17 years, and even my technical dive training (TDI Extended Range) wasn't as informative to me (the theory part, at least) as this book. Just the historical references, including detailed accounts of fatal deep diving accidents, could make a book on their own, and really instill in the reader the value of training & advances in technical diving equipment systems, and provide a deep appreciation for the very expensive lessons that have been learned over the past half-century of experience.
I found this book to be more detailed in many aspects than many Technical Diving training manuals, and much more interesting to read. Certainly, this book is not a replacement for officially sanctioned manuals, though when I (soon) become a Technical instructor I plan to make my students absorb this text as required "additional reading".
Nevertheless, due to a lack of further updates beyond the first revised edition of 1995, readers should be aware that this book is slightly dated or completely outdated in the following aspects:
- New approaches to using helium mixes at much shallower depths than before, and more attention to breathing mixtures such as hyperoxic and normoxic trimix
- New developments in dive computers, particularly multigas, gas-switching computers such as the Suunto Vytec, the VR3, and Nitek He, the latter two supporting helium mixtures.
- Pre-dive planning of dive Multi-level, multi-gas profiles using PC-based software
- Various general diving and decompression procedures have become more standardized and stricter since this book's publication, particularly issues like gas-supply redundancy.
Despite these and some other less significant issues, this book remains a very important text which I think all technical divers should read, at least as a historical reference. Of course, it would serve both TDI and the diving community greatly if Bret Gilliam & co. would produce a new revision to this book, Which is why I am giving this book "only" four stars.