Dean 's blue hole - wikipedia Dean 's blue hole Dean 's Blue Hole Dean 's Blue Hole is the world 's second deepest known salt water blue hole with an entrance below the sea level. It plunges 202 metres ( 663 ft ) in a bay west of Clarence Town on Long Island, Bahamas. Contents 1 Formation 2 References 3 Further reading 4 External links Formation A blue hole is a water - filled sinkhole with the entrance below the water level. They can be formed in different karst processes, for example, by rainwater soaking through fractures of limestone bedrock onto the watertable. Sea level here has changed : for example, during the glacial age during the Pleistocene epoch ( ice age ), some 15,000 years ago, sea level was considerably lower. Dean 's Blue Hole is roughly circular at the surface, with a diameter ranging from 25 to 35 metres ( 82 -- 115 ft ). After descending 20 metres ( 66 ft ), the hole widens considerably into a cavern with a diameter of 100 metres ( 330 ft ). The deepest known marine blue hole is Dragon Hole. References This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. Please help to improve this article by introducing more precise citations. ( June 2016 ) Further reading Wilson, William L. ( 1994 ). `` Morphometry and Hydrology of Dean 's Blue Hole, Long Island ''. Bahamas Journal of Science. 2 ( 1 ) : 10 -- 14. Archived from the original on 7 March 2012. External links Dean 's Blue Hole Dean 's Blue Hole entry and exact location on Bloosee Vertical Blue Coordinates : 23 ° 6 ′ 23 '' N 75 ° 0 ′ 31 '' W ﻿ / ﻿ 23.10639 ° N 75.00861 ° W ﻿ / 23.10639 ; - 75.00861 Retrieved from `` https://en.wikipedia.org/w/index.php?title=Dean%27s_Blue_Hole&oldid=800315117 '' Categories : Landforms of the Bahamas Sea caves Marine geology Underwater diving sites in the Caribbean Long Island, Bahamas Sinkholes of North America Hidden categories : Articles lacking in - text citations from June 2016 All articles lacking in - text citations Coordinates on Wikidata Talk Contents About Wikipedia Català Deutsch Español Français Italiano Norsk Русский Українська 中文 Edit links This page was last edited on 12 September 2017, at 19 : 26. About Wikipedia

Question: dean’s blue hole is one of deepest
Answer: salt water blue hole