Deep Dark Secrets
Incredibly Wonderful, Extremely Dangerous
Have you ever swam out in the sea and not been able to see the bottom? All you can feel is the freezing cold water beneath your feet; all you see is dark blue water extending to infinity.Have you ever heard of blue holes? Well, I never did until I read an article on Bahamas
If you’re an avid scuba diver or snorkeler, you’ve undoubtedly heard about Blue Holes. Blue holes are underwater caves or sinkholes which, from the top, appear circular and intensely dark blue. They’re often surrounded by lighter blue waters that are more shallow as well as sand, so they almost look like deep blue eyes in the middle of the ocean. Blue holes can occur all over the world, and some of the most famous are in the Bahamas , Belize and even Ohio.
These submerged caves—found both on land and in the sea—are actually among the least studied and most threatened habitats on Earth.
Extremely Dangerous
Blue holes can run extremely deep underground, with one Bahamian blue hole exceeding 600 feet (180 meters) below sea level, and contain a series of maze-like passageways going miles in many directions. These cave systems can transition from giant rooms to tiny holes that divers must remove all of their gear in order to squeeze through. To add to the challenge, currents reverse in the ocean caves, making timing of dives critical. All in all, a difficult place to explore and even more challenging to achieve the range of scientific and filming goals that the team has on their agenda.
Blue holes can run extremely deep underground, with one Bahamian blue hole exceeding 600 feet (180 meters) below sea level, and contain a series of maze-like passageways going miles in many directions. These cave systems can transition from giant rooms to tiny holes that divers must remove all of their gear in order to squeeze through. To add to the challenge, currents reverse in the ocean caves, making timing of dives critical. All in all, a difficult place to explore and even more challenging to achieve the range of scientific and filming goals that the team has on their agenda.
"These holes are a time capsule of evolutionary science"Starved of light and oxygen that typically fuel decay, the blue holes have produced an array of stunningly preserved fossils, from brown bones of ancient native Lucayans to shells of long-extinct land tortoise and freshwater crocodiles once thought to live only in Cuba.
The caverns are also places of weird life and other-worldly beauty, a combination that put the expedition on the cover of August's National Geographic.
The holes are populated by blind cave fish, strange and tiny crabs and shrimp and masses of microbes, including never-before-seen "extremophiles" adapted to survive the harsh environment. Ancient fossilized reefs form the walls and some passages are labyrinths of gnarled but fragile stalagmites that can evaporate in puffs of silt if struck. 5 AMAZING BLUE HOLES
1. Great Blue Hole, Belize
First discovered by Jacques Cousteau, one of the world’s most famous divers and marine conservationists, the Great Blue Hole in Belize is the best of the bunch, and every diver’s dream. Measuring 305m (1,000 ft) across and 123 m (400 ft) deep, the Blue Hole is almost perfectly circular and can be found in Lighthouse Reef Atoll, about 60 miles from Belize City.Starting at around 30-33 meters, the limestone formations become more intricate with depth, but few get to see what they look like as most divers are only qualified to go to a depth of around 30 meters – although, when it comes to diving in blue holes, many flout the rules.
2. The Blue Hole, Dahab
Until only about 25 years ago, Dahab was a tiny Bedouin fishing village on the Sinai coast, about 50 miles from Sharm el-Sheikh to the south. Now it’s known worldwide for having great windsurfing conditions and some of the best shore diving anywhere.
Only a short drive north of the main centre of Dahab is the notorious Blue Hole, known among diving circles as the ‘World’s Most Dangerous Dive Site’. It can be accessed from the shore and is around 130m deep, but with a tunnel at 52 m many divers are tempted to go beyond the recreational diving limit of 40 m to experience everything the Egyptian blue hole has to offer, including nitrogen narcosis for the unfortunate few. Because the entrance is hidden and difficult to spot, divers looking for a way in often go too low, increasing the risk of ‘the bends’. Some are never seen again.
3. Dean’s Blue Hole, Bahamas
Dean's Blue Hole, lying in a beautiful bay southeast of Long Island's Capital Clarence Town, is the World's deepest blue hole, plunging 663 feet (200 meters) to the bottom of the Atlantic Ocean. The blue hole is oval at its surface, with a diameter ranging from 80 to 120 feet (25 to 37 meters). Descending 60 feet (18 meters), the hole widens considerably into a cavern with a diameter of up to 330 feet (100 meters). Although visited by experienced divers from all over the world, Jim King become the only person to sink all the way down to the ocean floor in September, 1992, performing a mixed gas dive. Many other local and world records were achieved, the most recent by Newzealand's William Trubridge and his team Vertical Blue. During the month of April, 2008, he set an amazing world record in the purest form of freediving, an entirely unassisted 'constant weight no fins' dive, to a new mark of 282 feet (86 meters). A few days later, he pushed the new limit for 'free immersion' diving, descending and ascending by pulling on a line, to unbelievable 354 feet (108 meters).
4. The Blue Hole, Gozo
Not clearly as visible from the surface, the mouth to Malta’s Blue Hole starts at 7 m deep, and is the most popular dive site on the islands.Located within the blue hole is a cave at 15 m below where shoals of tuna, groupers and barracuda are often found hovering by the large boulders and rocks. Divers can swim through a short tunnel, or chimney, to get to a different area within the hole which has great coral gardens and reefs teeming with marine life – quite amazing considering how fished out many parts of the Mediterranean are.
5. The Blue Cave, Korcula
If you enjoy the open sea and watching marine life you should make an effort to visit the Blue Hole at least once in your life. It’s an experience you’ll always remember!
