November 26, 2008--Some 3,700 World War II shipwrecks lie submerged in the Pacific Ocean.

Encased in coral, host to abundant sea life, and popular among scuba-loving tourists, some of these vessels also contain noxious cargo including oil, diesel, gasoline, chemicals, and even unexploded ordnance.

Concern about the dangers of corrosion is prompting increased investigation of wrecks that may pose hazards to marine life, beaches and local economies.

Here, scuba divers explore the wreck of the coral-covered U.S.S. President Coolidge, a luxury cruise liner-turned-troop ship that was sunk by mines in 1942 as it entered the harbor of Vanuatu's Espiritu Santo Island.