Great Blue Hole

The Great Blue Hole is a large submarine sinkhole located in the coast of Belize. It lies near the center of Lighthouse Reef that is 70 km (43 mi) far away from the mainland and Belize City. The hole is circular in shape, over 300 m (984 ft) across and 124 m (407 ft) deep. It was formed during several episodes of quaternary glaciation when sea levels were much lower. Analysis have shown that formation took place 153,000, 66,000, 60,000, and 15,000 years ago. As the ocean began to rise again, the caves were flooded. The Great Blue Hole is a part of the larger Belize Barrier Reef Reserve System, a World Heritage Site of the United Nations Educational, Scientific and Cultural Organization (UNESCO).

Photo taken from National Geographic.

This site was made famous by Jacques-Yves Cousteau, who declared it one of the top ten scuba diving sites in the world.
This is a popular spot among recreational scuba divers who are lured by the opportunity to dive in crystal-clear water and meet several species of fish, including giant groupers, nurse sharks, and several types of reef sharks such as the Caribbean reef shark and the Blacktip shark.

View from the bottom of Blue Hole.