At the bottom of Belize’s Great Blue Hole, inside a pitch-black dead zone where oxygen doesn’t exist, submersible pilots found the remains of two missing divers. Jacques Cousteau explored this 410-foot-deep sinkhole in 1971 but never reached its floor, and nobody tried for nearly five decades.
A near-perfect circular sinkhole sits in the Caribbean Sea about 60 miles off the coast of Belize City. Known as the Great Blue Hole, it measures roughly 300 meters across and drops to a depth of about 125 meters. The formation lies within the Lighthouse Reef Atoll and is part of the Belize Barrier Reef Reserve System, which received UNESCO World Heritage status in 1996.The hole is visible from or…