The Great Blue Hole is a gigantic sinkhole off the coast of Belize that measures 984 ft across and 407 ft deep. The blue hole was formed through karsting episodes of limestone where the limestone dissolves. The dissolution of limestone occurs differently during high and low sea levels, with the Great Blue Hole likely forming over the course of several glaciation cycles. Divers from around the world visit this UNESCO world heritage site to enjoy the natural wonder of the hole and diverse marine life.