Earlier this week, Australian marine biologist Johnny Gaskell posted an amazing video to his Instagram account, showing a gorgeous blue hole in the Great Barrier reef, reports News.com.au.
According to Instagram, Gaskell and some friends spotted the hole off the coast of the Whitsunday Islands while looking at images of the reef on Google Maps. They decided to visit the hole in person, finding a 45 to 60-foot-deep, 450-foot-wide chasm in the middle of the reef, filled with birdsnest and staghorn corals. He unofficially dubbed the feature "Gaskell's Blue Hole."
"We may very well be the first to ever dive Gaskell's Blue Hole as it was so far offshore and hidden deep within one of the Great Barrier Reef's biggest lagoons," he writes on Instagram.
What was most surprising to Gaskell was that the corals in the blue hole showed no lingering damage from a category 4 cyclone that passed over the area earlier this year—a find that could have implications for overall reef health.
“The protected coral living in the hole could help other parts of the reef regenerate," Gaskell tells Andrea Booth at SBS World News. "Cyclone Debbie destroyed many delicate colonies early this year, but these corals were protected and escaped unharmed. This is extremely important for the ecology of the reef, as this lagoon will play a big role during this year's coral spawning. Recolonization to damaged areas will be the key to this part of the reef bouncing back.”
Gaskell is keeping the location a secret to protect it from an influx of divers. But because of this, it's difficult to determine if the blue hole has, in fact, never before been seen. Some Instagram commenters claim it is a well-known dive spot in the scuba community, though this fact is not yet confirmed.
So what is a blue hole?
Many of the features are essentially ancient sinkholes that form in carbonate rocks, such as limestone. These rocks are soft and will wear away over time—even dissolving under the slight acidity of rain.
These mysterious features actually initially form on land, during periods when much of Earth's water was locked away in ice, which causes sea level to dip lower than ever before. When the ice melts, the sinkhole becomes submerged in the flooded landscape.
How the sinkholes themselves form, however, can vary. Though some may form from the percolation of acidic rainwater that eats away at the soft rocks, others come from underwater bacterial activity, which also forms acids, according to the Bahamas Cave Research Foundation.
Gaskell’s hole isn’t the only recently discovered blue hole. Just last year, the world’s deepest blue hole, the 987-foot Dragon Hole, was spotted in Paracel Islands in the South China Sea. Researchers believe that cavern differs from other holes previously studied and was likely the result of an unknown process. But by far the most famous blue hole is the Great Blue Hole at Lighthouse Reef in Belize, a 480-foot diver's paradise 60 miles off the coast of Central America.
Shallow or deep, elongated or circular, all of these blue holes are bursting with life. The structures often harbor a range of species of coral and other creatures that differ from the surrounding shallow seas. So no matter where or how they formed, all are fascinating environments to explore.