Dean’s Blue Hole is the world’s deepest salt water blue hole. The entrance of the hole is below the sea surface, and it descends to a depth of 663 feet, at the bottom of which is a huge underwater cavern. Thanks to its proximity to Clarence Town in the Bahamas (it can be reached by swimming, no boat required), it is a very popular dive spot.
The waters of the Bahamas were among the last on Earth to be settled. Dean’s Blue Hole was probably not discovered until well into the colonial era, and almost certainly not explored until the 20th century. The world’s free-diving record was set here in 2010 when diver William Trubridge reached a depth of 302 feet.
Dean’s Blue Hole is a product of the ice ages, when the sea levels were much lower and rainwater eroded the limnestone the same way caves on land are formed. The limestone ultimately collapsed into a sinkhole to a significant depth, forming a cavern at the bottom over three hundred feet in diameter. The ecosystem here is fascinating and a little frightening as it is a haven for barracuda.
Dean’s Blue Hole is a very accessible dive site, being just a few feet walk from the shore. It is also largely sheltered from rough water. Because of this it is a popular site not only for experienced divers but also for more casual explorers (though not children). Web: www.deansbluehole.org (official website).