World’s deepest underwater cave discovered in Czech Republic

A team of explorers recently found the world’s deepest underwater cave located in the eastern part of the Czech Republic. A Czech-Polish expedition, led by the legendary Polish diver Krzysztof Starnawski, descended deep into the flooded limestone cave called Hranice Abyss and found it to be far deeper than previously thought. According to their measurements, the cave is 404 meters deep, 12 meters deeper than the previous record holder, 392-meter-deep Pozzo del Merro in Italy.

Hranice Abyss, photo: Lenka KratochvílováHranice Abyss, photo: Lenka Kratochvílová I spoke to diver David Čani, who has been exploring the Hranice Abyss for years, to tell me how it all started:

“The first exploration of depth in Hranice Abyss started in 1961 and the depth back then was only six metres. In 1963 it was twelve metres and it continued like that for a long time. I became part of the team in 2003 but it was not my first experience. I have been going there to assist the divers since 1997.”

How did the Polish diver, Krzystof Starnawski, become involved?

“We have known Krzystof for a long time. We have been diving and discovering some other caves together. I think it was in 2000 when he did a 188- metres dive. Back then, none us could dive that deep, so we were using his skills and training. He basically became part of our team and since then we have been working together not only in the Hranice Abyss.”

So you invited him to take part because he is one of the few people who can dive as deep as 200 metres.

“Nowadays, he is actually diving close to 300 metres. I don’t know anyone who can dive so deep and I think that he is one of the best, especially for exploration in deep parts of the cave.”

One of the explorations took part in 2014, and that’s when you reached the depth of 200 metres. And as far as know, you also took part in that expedition.

Hranice Abyss, photo: Fext, CC BY 3.0Hranice Abyss, photo: Fext, CC BY 3.0 “Yes, I was there and it was a very important dive for us. Krzystof was lucky enough to get through a restriction around 195 metres and discovered that it had a huge continuation underneath. I was a deep safety diver on that particular expedition. I was waiting at 150 metres for him, carrying bail out tanks and so on.”

Can you explain in greater detail the role of safety divers?

“When a diver goes for a deep dive, there are not many options how to secure him. In mountain climbing it is called a dead zone. It is really difficult to help or assist a person who finds himself in trouble.

“If a person dives below 150 metres it is difficult to provide him with some kind of support. The main thing is to be there with him and support him in psychologically. And the only thing you can give him is some extra gas, if he needs it.”

So in 2014 you discovered that the Hranice Abyss was probably much deeper than you previously thought.

“Definitely. We saw a huge opening that showed us that it was possible to dive even deeper. In the previous expeditions we sent some probes and ROVs through the restriction, but it was so small that we were not able to get through it.

But when Krzystof squeezed through the teeny tiny restriction, he discovered that the opening was big enough and that it was possible to dive there and explore the deeper parts.”

Hranice Abyss, photo: Czech TelevisionHranice Abyss, photo: Czech Television Have you always suspected the Hranice Abyss might be the world’s deepest cave?

“According to the geological research the limestone massive, which is part of this region, is up to 1.3 kilometres deep, so we knew that the cave might that deep as well.”

So can you tell me more about the list dive? i know you had to employ a special robot to measure the depth…

“We call it ROV, a remote operated vehicle. It is basically a little robot which is controlled from the surface. Fore that dive Krzystof went down to 200 metres to secure the line for the ROV to follow through the restriction to the deeper part. At that moment, nobody really believed that we could do it, it was just a test. Nobody knew we would be lucky enough to follow the line along the wall of the cave all the way to 404 metres.”

That must have been a huge surprise…

“That’s for sure. Nobody was prepared for it. Like I said, it was supposed to be just a test, but we accidently made this discovery.

Can you tell me more about the Hranice Abyss. What is unique about it?

“The unique think about it is that there isn’t regular water. It is mineral water, saturated with CO2,which makes it more complicated for divers, because it is irritating and it itches the skin. There is also not much light in the cave and the temperature of the water keeps changing.”

Hranice Abyss, photo: Czech TelevisionHranice Abyss, photo: Czech Television You have been diving all around the world. What do you find attractive about the diving locations in the Czech Republic?

"Most of the other places I have visited, in Italy Mexico Florida, the caves are usually much friendlier, there is better visibility and warmer temperature. Diving, especially in Moravian Karst, is much more challenging and this is what attracts me.”