A blue hole is a submarine cave or underwater sinkhole. They are also called vertical caves.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.(Wiki)There are many different blue holes located around the world, from Belize and the Bahamas to the Red Sea.
Great Blue Hole
Among these blue holes- Great Blue Hole of Belize is believed to be the world’s largest sea-hole . Its almost perfect circular shape made it very popular amongst tourists who often visit this place. This place is most attractive for scuba divers who are exploring the depths of this hole. It is known that there are a plenty of cave networks in this place. Divers are also attracted with plenty of rare animal species and forms of life which can be found only in this place.
|NASA Earth Observatory|
It lies near the center of Lighthouse Reef a part of Belize Barrier Reef Reserve System, a small atoll 70kilometres (43 mi) from the mainland and Belize City.
Shape and Size
The hole is impressively circular in shape, over 300 meters (984 ft) across and 124 metres (407 ft) deep. Geologist found out that , it has been created as a cause of sea level increase about 65,000 years ago.
Following youtube video may help the readers and viewers, to visualize this blue hole with some good narration and geographical facts. This Natural Wonder is a world heritage site of UNESCO