Dean's Blue Hole is the world's deepest blue hole, which plunges 202 m to the ocean floor, west of Clarence Town on Long Island, Bahamas. Dean's Blue Hole is roughly circular at the surface, with a diameter ranging from 25 to 35 m. After descending 20 m, the hole widens considerably into a cavern with a diameter of 100 m. In April 2007, William Trubridge broke a free-diving world record in the blue hole reaching a depth of 84 metres (276 ft) without the use of fins. In April 2008, during the Vertical Blue 2008 free-diving competition, a total of 25 national records and 5 world records were broken. During this event, William Trubridge broke his own world record in the Constant Weight Without Fins (CNF) category reaching 86 metres (282 ft) as well as breaking the record in Free Immersion (FIM) at 108 metres (354 ft). In April 2009, Australian Walter Steyn achieved a new Australian free-diving record of 100 metres (330 ft) at Dean's Blue Hole Blue holes are the results of rainwater having soaked through fractures of limestone bedrock onto the watertable of glacial sea levels during the Pleistocene epoch (ice age), some 15,000 years ago. The maximum depth of other known blue holes and sinkholes is 110 metres (360 ft), which makes the 202 metres (663 ft) depth of Dean's Blue Hole quite exceptional.
Dean's Blue Hole is roughly circular at the surface, with a diameter ranging from 25 to 35 metres (82–110 ft). After descending 20 metres (66 ft), the hole widens considerably into a cavern with a diameter of 100 metres (330 ft). At 203 meters (660 feet), Dean's is the deepest Blue Hole in the world, and the second largest underwater chamber. It is enclosed on 3 sides by a natural rock amphitheatre, and on the third side by a turquoise lagoon and powder white beach. There is never any swell or waves inside the Hole, and visibility is usually between 15 - 30 meters (50 - 100 feet). At the surface the Blue Hole is 25 x 35m (80 x 120 feet), but opens out after 20m (60 feet) into a cavern with a diameter of at least 100m (330 feet). It is still unknown how Dean's Blue Hole was formed, as it is almost twice as deep as any of the other Blue Holes in the Caribbean that were formed when limestone chambers caved in from above. One hypothesis is that a much deeper cave slowed moved upward as its ceiling eroded away. A school of tarpon hang in the shadows at 30m (100 feet) and a friendly turtle sometimes comes into the hole for a break from the ocean swells. The coral caves and sand banks on the side of the entrance harbour all kinds of tropical reef fish, groupers and snappers.
Clues picked up from deeperblue: "There is very little tourist development except on the north end, and that is low key. Most of the population are farmers or commercial fishermen diving for lobster and fish. You will need a vehicle. Car rentals are available, but a little rough by first world standards. Boat rental businesses don't exist.One unfortunate thing, the Bahamas are expensive in US dollars, everything you consume will cost double stateside prices. The best way to do Long Island is get friendly with the natives. There are lots of very good divers there, especially around Salt Pond, and they will be interested in what you're doing. The locals are fantastic people, but the culture takes some understanding. Bahamians don't like to tell you no. Often, yes really means no. You can't push'em. This, the slow pace of life, and limited local resources can make you crazy. The ocean diving is outstanding, but access is tricky. Get someone to take you to Millers, the best structure is just south of the tiny harbor. You can dive the reefs from shore, but that involves a pretty good swim in Very sharky water. I don't reccommend it. For some reason, the reef sharks there can be aggressive as heck. Unless you are in Clarencetown, which has a big harbor, a small skiff in the back of a pickup launched off the beach is by far the best way to handle it. Some of the reefs off Stella Maris (northern end) have suffered much in recent years, I'm not sure about Millers or Clarencetown. Diving out of and just north of Clarencetown used to be fabulous, , 30 meter plus vis(40 m at times), big ledges, sharks sleeping in caves. Acres of huge staghorn in 50-60 ft of water, unbelievable. Clarencetown has some houses for rent, probably not much in Salt Pond. From the description on the above website, it must be closer to Clarencetown, near the end of a section of coast that is sheltered from the southeast trade winds. That should be real good for ocean diving conditions. Spearfishing is fine, and should be fairly productive in deeper water. The reefs, when I saw them, were spectacular. The sharks can be aggressive, (much more than in most of the Bahamas) but if you are diving buddies and a boat(with driver) is close, they shouldn't be a serious problem. Its the long swim with no boat that would make me nervous. You might want to rethink diving offshore, there should be some kind of wall diving, a huge vertical drop that starts about 150 ft and goes to a thousand or more. Very spectacular, especially if you have the depth capacity to get below the lip. One thing for non-local spearos. Big preditors can poison you every now and then. I don't eat big anything, cuda over 5 pounds, black and yellowfin grouper over 15, hogfish over 12, muttons over 6 or 8. No jacks period. Nassau grouper of any size are ok. Ciguatera is not all that common, but is a very nasty, long term, nerve poison."
Better to be called "Green Hole" (the surrounding foliage growth giving it an intensily deep - green colour ... suggesting infinite depth), Dean's Hole is situated in a marvelous setting: About one hour south from Stella Maris, north of pretty harbour village Clarence Town, it sits right at the Atlantic's edge, well protected by high cliffs, enjoying inland bordering by a gorgeous beach and bay. It's just a few steps from your vehicle to the beaches' edge - and there, you stare onto the surface of seemingly infinite depth. It looks inviting - and mysterious. It looks haunted, making you keenly appreciate the ground under your feet! Just put on your goggles, and with a few strokes - you are over it! Take heart, dive in ... just to the edge, perhaps, some 15' down. You got the idea! While swimmers and snorkelers can readily enjoy the uniqueness of this site, above and underwater, for a diver, putting on a tank and going in is a must ... this type of Blue Hole is diving for mystique, diving for depth (caution - naturally we advocate limiting this to safe depths!). It's diving for 'feeling' ... for intensity of awareness: Of sound, of stillness, of the look down, the look up. Yes - you will see some small reeflife along the upper edge ... and you may encounter an occasional turtle, or perhaps a small school of tarpon. Yes - we have seen Porpoise here ... but only by chance. The real thrill is this: You will have been in the World's deepest known Blue Hole - and the World's second largest, waterfilled, cavern body! And the World's eighth largest cave body of any type! Hole starts at depth 6 (18´) meters. 18 (60´) meters wide at start, but about 75 (250´) meters wide further down, * Depth to bottom 200 (663') meters.
Walls dropping vertically all-around. There are tunnels and caves. Not much life inside apart from occasional stray shark. 1992, Jim King, President of Deep Breathing Systems, performed a Mixed Gas Dive to the bottom of Dean's Blue Hole. All known Blue Holes are the results of rainwater having soaked through fractures of limestone bedrock during ice age some 15,000 years ago. The Blue Hole is about 1km from Clarencetown, on the north (Atlantic) side of Long Island. Flights from Nassau are $85 one way ($170 return) to Deadman's Cay. There are local houses to be rented (probably about $100 - 150/ week). Food is reasonably expensive, but fish is easy to catch! Flights to Nassau usually leaves from Miami. This is the place where Will Trubridge traisn for his World record CNF attempts with Mike Lott. From here they will in the future give courses.
