This area off Colombo on Sri Lanka’s southwestern coast rewards intrepid divers with more than 15 known wrecks and warm, crystal-clear water if dived in the right season.

After unleashing the most powerful weapons in history at the end of World War II, the U.S. military needed more data. Today, the Pacific atoll where it tested its doomsday bombs is a Holy Grail for divers.

Palau has plenty to offer traveling scuba divers, including bumphead parrotfish spawning and night diving experiences.