Starfish

Starfish, by Peter Watts, is the first book in the Rifters trilogy. I like this book and will buy the others new if they aren't available at my local used book store the next time I go in. The book is available online, so you can get a taste of it before you buy a copy. The author has information on Starfish here.

from the back of the book:

A huge international corporation has developed a facility along the Juan de Fuca Ridge at the bottom of the Pacific Ocean to exploit geothermal power. They send a bio-engineered crew - people who have been altered to withstand the pressure and breathe the seawater - down to live and work in this weird, fertile undersea darkness.

Unfortunately the only people suitable for long-term employment in these experimental power stations are crazy, some of them in unpleasant ways. How many of them can survive, or will be allowed to survive, while worldwide disaster approaches from below?

SF Crowsnest has a review. Strange Horizons calls it

an impressive debut from a Canadian scientist/writer who seems to enjoy tackling big topics like corporate greed and mismanagement, the resilience of the human spirit, and the wealth of things humans still don't know about Earth's deep ocean environments -- or each other.

SFReviews.net says,

Its grimness will not appeal to everyone, but if you like your fiction both edgy and dark in roughly equal measure, this unsettling trek into both the depths of the ocean and of the human psyche will leave you uneasy for days.

The author suggests Sarah MacLachlan's "Possession" as a mood-setting theme song for the book:

He lifts up the music of Jethro Tull as having "provided ongoing inspiration". Here's Aqualung:

Jethro Tull - Aqualung @ Yahoo! Video