If you wanted to know anything about Hawaii anchialine pools and their amazing and largely endemic inhabitants, this book is a great introduction.
Anchialine pools are usually brackish pools that are usually fed by underground passages in lava or limestone. They are populated by a unique and sometimes rare collection of invertebrates. One in particular, Halocaridina rubra or opae 'ula, is commonly sold as an aquarium pet or in miniature biospheres.
The authors have written a concise yet easy to read guide to these pools, the species, the fragile nature of their ecosystems, and their vulnerability to over harvesting, habitat destruction, introduced species, and development.
The book is also full of gorgeous photographs, many taken by the authors and by others for which they give full credit. It's not a large book, at 112 pages, but it is a gold mine of information.