Book One in the Rifters Trilogy.
Book Two: Maelstrom
Book Three: Behemoth
When civilization needs someone to run generating stations three kilometres below the surface of the Pacific, it seeks out a special sort of person for its Rifters program. It recruits those whose histories have pre-adapted them to dangerous environments, people so used to broken bodies and chronic stress that life on the edge of an undersea volcano would actually be a step up. Nobody worries too much about job satisfaction; if you haven't spent a lifetime learning the futility of fighting back, you wouldn't be a rifter in the first place. It's a small price to keep the lights going, back on shore.But there are things among the cliffs and trenches of the Juan de Fuca Ridge that no one expected to find ...
Also by Peter Watts on obooko:
Author's website http://www.rifters.com