Explore the world's deepest underwater caves in the Czech Republic

People combine with robots to discover the world's deepest underwater cave in the Czech Republic. This cave, called Hranická Propast, reaches a dizzying depth of 404m (1,325 ft), deeper than the second deepest cave in the world, Pozzo del Merro in Italy, about 12m.

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Polish diver Krzysztof Starnawski began diving at Hranicka Propast and identified it as the deepest cave in the world 20 years ago.(Image source: Marcin Jamkowski / National Geographic).

The Polish diver - Krzysztof Starnawski first discovered the Hranická Propast cave in 1999. The limestone terrain structure he found made him believe that the cave could be much deeper than the location. He can dive to. So Starnawsk divers led the Czech expedition - Poland to explore this cave, supported in part by National Geographic. This expedition team has dived many times down the Hranická Propast cave in the past two years to gather more data. Recently, this limestone basin has been measured by the support of a remote operator vehicle (ROV) and identified the deepest Hranická Propast cave in the world.

On a 2014 dive, Starnawski dived to a depth of 200m (656 ft) - where he thought it was the bottom of the cave. However, he found a narrow hole leading to an enlarged tunnel, far beyond the probe that Starnawsk used to measure the depth of the cave. The depth of this tunnel is about 384m (1260 ft), only slightly lower than the water depth of Pozzo del Merro 392m.

"Krzysztof Starnawski is a diver in very deep caves, so he is very passionate about exploring the deepest parts of this cave system ", Marcin Jamkowski - a member of the expedition and also a home explorer film - answered the Live Science newspaper.

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With the help of an underwater remote control, the expedition team can measure the depth of this cave and explore the bottom of this limestone abyss.(Image source: Marcin Jamkowski / National Geographic)

Returning to the cave last year, Starnawski found that the narrow slots were wider and he could get in to a depth of 265m (869 ft). He dropped another probe, this time the probe could reach "the bottom" at a depth of 370m (1214 ft), which was probably the tip of the debris from collapsed sections.

"In the end, on September 27 a exploration dive determined the actual depth of the cave, breaking the record of the depths of the caves. The expedition used ROV technology to touching down to the bottom of the cave, because the 400m depth was beyond the limits of the diver's compressed air tank, "Jamkowski said.

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"There have been a number of dives done by the oil industry, reaching such depths (called" deep diving "), but they last for about a month. done in caves like this, so it was obvious that the choice was to send robots to places where humans could not be reached , " Jamkowski wrote in an email.

According to Jamkowski, as soon as the expedition discovered the depth of the cave, they found fallen trees, wood and branches at the bottom. This shows that this cave has changed from its original shape. With the current structure, there are no debris falling from the entrance of the cave.

They also found that this cave is really big, because it appears a natural stone feature or a line "corroded by spring hot water , " Jamkowski said. The team continues to explore and delve deeper into this cave.