The Great Blue Hole is a large submarine sinkhole off the coast of Belize. It lies near the center of Lighthouse Reef, a small atoll 70 kilometres from the mainland and Belize City. The hole is circular in shape, over 300 metres across and 124 metres deep. It was formed during several episodes of quaternary glaciation when sea levels were much lower – the analysis of stalactites found in Great Blue Hole shows that formation took place 153,000, 66,000, 60,000, and 15,000 years ago.
A blue hole is a cave (inland) or underwater sinkhole. They are also called vertical caves. There are many different blue holes located around the world, typically in low-lying coastal regions. The best known examples can be found in Belize, the Bahamas, Guam, Australia(in the Great Barrier Reef), and Egypt (in the Red Sea).
Blue holes are roughly circular, steep-walled depressions, and so named for the dramatic contrast between the dark blue, deep waters of their depths and the lighter blue of the shallows around them. Their water circulation is poor, and they are commonly anoxic below a certain depth; this environment is unfavorable for most sea life, but nonetheless can support large numbers of bacteria.
The deepest blue hole in the world—at 202 metres (663 ft)—is Dean’s Blue Hole, located in a bay west of Clarence Town on Long Island,Bahamas. Other blue holes are about half that depth at around 100–120 metres (330–390 ft). The diameter of the top entrance ranges typically from 25–35 metres (82–115 ft) (Dean’s Blue Hole) to 300 metres (980 ft) (Great Blue Hole in Belize).
Related articles and websites:
- Wikipedia- Great Blue Hole
- Wikipedia- Blue Hole in general
- Wikipedia- Sinkhole
- The Great Blue Hole at Lighthouse Reef
- Quick Guide To Ambergris Caye
- Large Pictures of Ambergris Caye, Belize
- Stalactites in the Great Blue Hole