wes c skiles

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Blue Hole Caves

A blue hole is a cave (inland) or underwater sinkhole. They are also called vertical caves. There are many different blue holes located around the world, typically in low-lying coastal regions. The best known examples can be found in Belize, the Bahamas, Guam, Australia (in the Great Barrier Reef), and Egypt (in the Red Sea).

Blue holes are roughly circular, steep-walled depressions, and so named for the dramatic contrast between the dark blue, deep waters of their depths and the lighter blue of the shallows around them. Their water circulation is poor, and they are commonly anoxic below a certain depth; this environment is unfavorable for most sea life, but nonetheless can support large numbers of bacteria.

Blue holes formed during past ice ages, when sea level was as much as 100–120 metres (330–390 ft) lower than at present. At those times, these formations were targets of the same erosion from rain and chemical weathering common in all limestone-rich terrains; this ended once they were submerged at the end of the ice age.  (Wikipedia: x)

(Click on individual photos for sources.)

“Even with the bright lights and crystal clear water, it’s just a heart-pounding, black abyss beneath us. Most people associate claustrophobia with cave diving, but floating over nearly bottomless voids like this tends to raise the hairs on your neck more so than the tight places do. As cave divers you never really think about how comforting a cave floor is until you don’t have one. At times it feels like black tendrils are reaching up from the void and trying to pull you down. Keeping a big team like ours at relatively the same level is critical for safety reasons: it seemed like one or two members were constantly drifting down. All of us have lost friends to the lure of descending too deep into the unknown.” - Wes Skiles