The world’s most famous blue hole is, arguably, Belize’s Great Blue Hole, but there are several others – and some are even deeper than this famed 124-metre flooded sinkhole.
One example is Dean’s Blue Hole on Long Island in the Bahamas, which plunges down for 202 metres. For context, the Statue of Liberty measures 93m metres from the ground to the tip of the flame. So, if you put two Lady Liberties one on top of the other in Dean’s Blue Hole, you still wouldn’t see her torch peeking above the surface.
Despite these staggering stats, Dean’s Blue Hole takes the bronze medal for the world’s deepest, behind the 420m deep Taam Ja’ Blue Hole in Mexico and the 300.89-m-deep Dragon Hole (Yongle Blue Hole) in the South China Sea.
Blue holes like these are a type of underwater sinkhole. “The ocean floor suddenly falls away hundreds of feet into a round, gaping, steep-walled maw big enough to swallow a small ship,” Woods Hole Oceanographic Institution (WHOI) explains on its website.
During the Ice Age, these were once areas of limestone on land. Over time, the elements slowly ate away at the rock, creating a cave system as it dissolved away. After many years, the roof of the cave could no longer hold up.
“Their roofs eventually caved in, leaving deep shafts open in the Earth,” adds WHOI. “When the ice age ended and sea levels rose again, these holes flooded, creating deep vertical caverns in what is now the seafloor.”
Unlike the Great Blue Hole, which sits in the middle of the vast ocean, Dean’s Blue Hole is so close to land that you can easily swim out from the beach and watch the sand suddenly vanish into its dark abyss. Some thrill-seekers even leap off the nine-metre cliff into the water.
Its calm conditions make it a popular spot with freedivers and is the location of the annual Vertical Blue Free Diving Competition. If you are a freediver, always follow safety protocols and be aware of the potential dangers of deep diving – people have died here.
But tourists don’t just visit for the pretty beach or the spectacular drop off. Dean’s Blue Hole is known for its ‘sand falls’ where sand pours off the rim and disappears below like an underwater waterfall. The eerie phenomenon looks like a monstrous plume of smoke being dragged down into the darkness of the hole below.
Those who come for the blue hole might stay for the vibrant marine life. Long Island has several spots where scuba divers and snorkellers have the chance of seeing bright corals, bustling communities of reef fish and even grimacing barracuda and reef sharks.
