Instruct: Classify Amazon reviews into positive or negative sentiment
Query: A good book if you know nothing about deep or mixed gas diving, but want only a broader over view

The book is getting old, but then history stays history. The book should be titled deep air diving as that is what this book is more about. Has a nice history of deep air diving, plus some highly informative text on mixed has diving. Also loads of information on the problems when diving deep, both on air or mixed gas. All this is explained in well-understood text. The author's humor is refreshing. But what this book does best, is it makes you think for yourself, and that is worth more than double its price. If you are a stick to the rules person, then you probably would not like this book much. But if you are one for finding new horizons and limits. Give it a go.