Dean’s Blue Hole

A 202 metre shaft that opens into a 100 metre cavern

Dean's Blue Hole drops 202 metres from a protected bay west of Clarence Town on Long Island in the Bahamas. It is the third deepest blue hole known, after the Taam Ja' Blue Hole in Chetumal Bay and Dragon Hole in the South China Sea, and most blue holes are only about half as deep. At the surface the opening is roughly round and 25 to 35 metres across. Some 66 feet down the shaft widens into a cavern 100 metres in diameter, and on good days the visibility can reach 115 feet.

A blue hole is a water-filled sinkhole whose entrance lies below the surface. The Bahamas has the highest concentration of them anywhere, more than 200 around Andros alone. They began as caves during the last Ice Age and flooded as the ice caps receded and the sea rose. How this one opened is still unsettled: either a fault in the limestone let a corrosive solution rise through it, or a buried cavern collapsed and left a sinkhole. The hole is named after a Bahamian fisherman, and local legend calls it a portal to hell.

Depth and calm water made it a freediving venue. William Trubridge of New Zealand set a world record here in April 2010, reaching 92 metres without fins, and on December 14, 2010 went to 101 metres on a single breath using only his hands and feet. Trubridge ran the Vertical Blue competition at the hole, where in July 2025 Walid Boudhiaf set a Tunisian national record of 118 metres. The American freediver Nicholas Mevoli died here in November 2013 while attempting a national record. Nobody has been to the bottom. Guillermo Söhnlein, a co-founder of OceanGate who left that company in 2013, has announced a survey of the hole by remotely operated vehicle through his company Blue Marble Exploration, open only to scientists and professionals, with no start date given.