Belize Blue Hole by JayFC
The Great Blue Hole is a large submarine sinkhole off the coast of Belize. 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 of stalactites found in Great Blue Hole shows that formation took place 153,000; 66,000; 60,000; and 15,000 years ago.