Riptide: Agent Pendergast series

For centuries, treasure hunters have sought the lost horde of the notorious English pirate Edward Ockham. Clues led to the mysterious Water Pit on Ragged Island, Maine-but a curse left behind by the long-dead Ockham seems to be working. Every expedition has failed; the treasure seekers died in gruesome fashions. Now a new expedition has been mounted, using state-of-the-art computer technology and backed by tens of millions of dollars. It will all be worth it, if the treasure estimated to be worth $2 billion can be found. But modern technology, no matter how expensive, may not be enough to overcome the deadly secrets of the Water Pit.