great blue hole
A large and visually arresting marine sinkhole in the Caribbean, off the coast of Belize. It was made famous by an expedition of famed marine explorer Jacques Cousteau and his crew in the early 1970s. At 318 meters in diameter and 124 meters deep, the Great Blue Hole is a popular scuba diving spot (and the final resting place of at least three divers who met unfortunate ends in its depths).