World's Deepest Underwater Cave Discovered

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World's Deepest Underwater Cave Discovered
By Kacey Deamer, Staff Writer | September 30, 2016 11:05am ET

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World's Deepest Underwater Cave Discovered




Polish diver Krzysztof Starnawski began diving in Hranicka Propast, now determined to be the deepest underwater cave in the world, 20 years ago.
Credit: Photograph by Marcin Jamkowski/National Geographic

Man and robot teamed up to discover the world's deepest underwater cave in the Czech Republic.

The cave, called Hranická Propast, reaches a dizzying depth of 1,325 feet (404 meters). It is about 39 feet (12 m) deeper than what is now the world's second-deepest cave, Italy's Pozzo del Merro.

Polish diver Krzysztof Starnawski first explored Hranická Propast in 1999. The type of limestone formation he found led him to believe that the cave could extend a greater distance than his dives had taken him. So Starnawski led a Czech-Polish expedition to explore the cave, supported in part by a National Geographic grant, which included numerous dives over the past two years to collect more data. The limestone abyss was recently measured with the assistance of a remotely operated underwater vehicle (ROV), and determined to be the world's deepest.

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 During a 2014 dive, Starnawski reached 656 feet (200 m) deep, which he believed to be the bottom of the underwater cave. However, he found a narrow opening that led to another vertical tunnel extending beyond the probe Starnawski was using to measure the cave's depth — the line ran out at 1,260 feet (384 m), just shy of Pozzo del Merro, which measures 1,286 feet (392 m) deep. [Amazing Caves: Pictures of the Earth's Innards]

"He is a deep-cave diver, so he was keen to explore the deepest parts of the system," Marcin Jamkowski, a member of the expedition team and an adventure filmmaker, told Live Science.
With the assistance of an ROV, the expedition team was able to measure the cave's depth and explore the bottom of the limestone abyss.
With the assistance of an ROV, the expedition team was able to measure the cave's depth and explore the bottom of the limestone abyss.
Credit: Photograph by Marcin Jamkowski/National Geographic

Returning to the cave last year, Starnawski found the narrow passage had widened and he was able to squeeze through to a depth of 869 feet (265 m). He released another probe, this time hitting "bottom" at 1,214 feet (370 m), which was likely the top of debris from the collapsed passage.

A dive on Tuesday (Sept. 27) finally determined the cave's actual, record-breaking depth. The expedition team used ROV technology to reach the base of the cave, because depths past 400 meters are beyond the limits of scuba diving, Jamkowski said.

"There had been some dives done by the oil industry to such depths (so-called "saturation diving"), but they last approximately a month, surface to surface," Jamkowski wrote in an email. "This can never be done in the cave like this one, so the obvious choice was to send the robot where the man can't go."

Once the team explored the cave's depths, they found fallen trees, logs and branches at the bottom, suggesting the cave had changed its shape, according to Jamkowski. The configuration of the current shaft would not accommodate natural debris to fall from the cave's entrance, he said.

They also found the cave to be surprisingly large, as it appears to follow a natural rock feature or a fault line "eaten by the hot water going from the deep spring," Jamkowski said. The team plans further exploration and research into the cave.

Original article on Live Science.
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   http://www.livescience.com/56333-worlds-deepest-underwater-cave-discovered.html

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Cave diving can be extremely perilous. Image Credit: CC BY 2.0 runeng
Divers have discovered an underwater cave in the Czech Republic which descends to a depth of 1,325ft.
Venturing through cramped, pitch black corridors of rock deep below the ground might seem like a terrifying ordeal at the best of times, but imagine donning scuba gear and attempting to dive down beneath the surface of an underwater cave... it's enough to make anyone feel claustrophobic.

For Polish diver Krzysztof Starnawski however it's all in a day's work, and now this intrepid cave explorer has managed to identify an underwater sanctum that is deeper than any other on Earth.

Situated in the Czech Republic, the cave, which is known as Hranicka Propast, was first explored back in 1999, but now following a two-year expedition, divers have discovered that it actually descends as far down as 1,325ft, making it the deepest underwater cave in the world.

Reaching the bottom was no easy task, especially as it is only possible for a diver to descend to around 400m using conventional scuba gear. To explore the rest of the cave, the team used a remote-operated exploration vehicle.

"My intention was not to achieve the deepest dive by a human, but to assist the exploration by the ROV," said Starnawski. "In this cave we wanted to explore beyond the 400-meter limit."

"It can't be done, so far, by a scuba diver in the cave. So I invited Bartlomiej Grynda from GRAL marine, with his custom-built ROV, to send the robot as deep as possible to explore the cave."

The team found fallen trees and branches resting on the cave floor which suggested that this immense cavern, which is thought to be part of a natural fault line, has been changing shape.

"The results were astonishing," said Starnawski.