Pressure - Brian Keene

Off the coast of Mauritius, the ocean floor is collapsing at a rapid rate. Carrie Anderson is a world-champion free diver and a marine biologist and she's going down there to find out what's happening and how to stop it. But what she uncovers is terrifying. She doesn't know exactly what it is, but she knows it's big, it's hungry and it's cold. The pressure builds for Carrie and her team to figure out what to do with this new sea creature as they must contend with a corrupt corporation - one that doesn't mind killing to keep things quiet.

Wow. This was interesting. At no point was the story boring. I couldn't wait to find out what was going to happen next. I either loved the characters or loved to hate them. I loved the setting - a gorgeous island with an underwater waterfall - why not put a monster down there?!