The Great Blue Hole
Situated near the center of Lighthouse Reef, this colossal marine sinkhole opened during past glacial periods when rising seas flooded a dry limestone cave system. The profile requires a rapid descent past the sunlit rim into the cavernous deep, where massive submerged stalactites hang beneath sheer rock overhangs. Sunlight diminishes quickly as you descend, leaving a cathedral-like ambiance accompanied by patrolling reef sharks cruising along the perimeter.
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