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This Diver Found the World's Deepest Underwater Cave

After 20 years of risky exploration and technical trial and error, Polish diver Krzysztof Starnawski finds the world’s deepest submerged cave. Get to know all 10 honorees, then vote every day for the People's Choice until December 16, 2016. The winner will be announced in January 2017.

Krzysztof Starnawski huddled with his team in a muddy limestone cavern on September 27, 2016, staring at a computer screen as a small yellow ROV sent back images of the underwater cave below them. Two decades of diving at this site, Hranická Propast in the eastern Czech Republic, had brought him to the brink of finding the world’s deepest underwater cave yet discovered.

The team shouted the readings on the ROV’s depth gauge. At 393 meters, they set a new world record, besting the previous champion, 392-meter Pozzo del Merro cave in Italy. Then the ROV passed 400, the team’s hoped-for milestone. At 404 meters, the cave’s floor, covered with a tangle of fallen trees and rock, came into view—and confirmed this cave as the deepest on the planet.

“It was an amazing moment,” Starnawski, 48, says. “Almost everything about it was difficult, but during this project, which started so many years ago, I made discoveries step by step and kept at it.”

That instant marked the high point in the Krakow-based diver’s 20-year exploration of Hranická Propast—first by diving himself, and then with an ROV designed to go deeper than humans have safely gone. Over a series of expeditions, Starnawski studied the cave’s unusual structure, which formed when a volcano-like gush of acidic mineral water ate through the soft limestone and created a vertical cave from the bottom up. He began to think that Hranická Propast could extend to a prodigious depth.

Recently, Starnawski completed dives that offered tantalizing clues. In 2012, he found a narrow opening about 200 meters down that led to another, previously undiscovered vertical tunnel. He lowered a probe through the shaft in 2014 and ran out of line at 384 meters.

Last year, Starnawski discovered that an underwater avalanche had widened the opening, and he was able to dive through it to a depth of 265 meters. He released another probe, and this time, it hit bottom at 370 meters, likely on top of a pile of rockfall debris.

Between dives, Starnawski identified a practical route for the ROV and modified the robot so it could survive the descent to the bottom. One solution was to encase its fiber-optic cable in Kevlar to protect it from the knife-sharp limestone. On the September 27 dive, technicians operated the robot from the surface, but Starnawski still needed to get it ready.

I started diving because I wanted to explore caves. Diving is a tool for exploration.
Krzysztof Starnawski Adventurer of the Year

Kenny Broad, 2011 National Geographic Explorer of the Year and professor at the University of Miami, says Starnawski’s achievements are “mind-blowing”—especially in light of the risks the extreme environment presents.

“Cave diving, versus open water diving, requires a different skill set, equipment configuration, and mind-set to deal with the multiple challenges,” he says. “They include an overhead environment with complex passageways that may go for miles in different directions, total darkness, zero visibility from silt, extremely tight squeezes requiring gear removal, and in some cases, extreme depths.”

Starnawski’s intense focus on planning, innovation, and training have kept him safe in these incredibly dangerous adventures, says Marcin Jamkowski, a diver and videographer on the team. In addition to exploring Hranická Propast, Starnawski has achieved dives in other underwater caves and in shipwrecks.

Adventure: What drew you to diving in the first place?

Starnawski: When I was about 18 years old, I went to a diving course and I tried to dive, but couldn't because I had problems with the pressure in my ears. I went to doctors, who told me that diving was out of the question. I was very disappointed. But then I start working in caves in Poland, and at the end of these caves I saw water. Every time, I asked, ‘What is in this water?’ No one knew.

Later, I biked around Europe, and at the end of the trip I drank a lot of alcohol to celebrate. (It was only one or two beers, but it was enough.) I happened to drink with a diving instructor. He showed me how to deal with the pressure, and I started diving right after that.

You've been diving in the same cave, Hranická Propast, for two decades. What kept you going?

In 2000, I dived to 181 meters, and I could tell this cave was ripe for exploration; the presence of the mineral water and limestone gave me the idea that it should be a very deep cave. But my knowledge and my equipment were not good enough. I needed about nine years to prepare equipment and learn more about deep cave diving [to get to this point], but I'm a competitor. If I can see a point forward, I have the energy to prepare for another dive.

What was going through your mind as you watched the ROV’s depth gauge move down from 380, to 384, to 393 meters, and beyond?

It was amazing, because it meant that we had found the deepest cave on Earth. But the most important thing that we saw on the camera was the continuation of this cave. That means we haven't finished this project—not yet. We finished only one part: crossing the 400-meter mark that we had set for ourselves four years ago. Now we know the cave is open; we can come back with a new project and go even deeper.

How deep do you think it will go?

I don't know, but it should be very deep! It's an amazing place, because the geology of this area is very interesting—first of all, it’s mineral water, which comes up from the bottom. And second, the limestone is about a thousand meters thick. That means that the cave should be about a thousand meters deep. The question is, is it possible to dive or push the ROV that deep? One problem is trees. In this vertical cave, one or two trees fell in every year for thousands of years. The bottom is a very dangerous area, especially for the ROV's cable. It will be a new adventure to get to the very bottom.

Compared to some other caves that you've dived in, how does Hranická Propast measure up?

It's not a very nice cave—it's quite cold, about 15°C; the rocks are black, and the visibility is only good at the bottom. The water has a lot of carbon dioxide—when you dive in it, it's like you’re taking a bath in Coca-Cola. You feel itching all around your face, all the skin that's not covered with the mask. You put grease on your face to protect yourself from the acidic water, but you can't protect yourself 100 percent, so you come back up with swollen lips. It looks like you’ve been stung by a bee!

Will you do anything differently the next time you dive in Hranická Propast?

If we take the technology that we have now, we can go 50, maybe 100 meters deeper, but we'd never get the ROV back to the surface. It's like climbing in the mountains—the real finish is when everyone is able to climb down to the base safely. If we want to think seriously about deeper exploration, we have to find new technology which gives us an almost 100 percent chance of an easy time going down and easy time coming back up.

What will you tackle next?

During the 20 years I’ve been diving in Hranická Propast, when I have had to wait for whatever reason, I dive in Albania, Mexico, and Macedonia. Each of these projects takes three, four, or five years, and I can jump from one to the other. Hranická Propast was the best, but these other projects are almost as interesting and are going well. Now I think I need a few months’ rest. Then I’ll spend a few months in Mexico teaching people cave diving.

What do you love most about diving?

Exploration. I started diving because I wanted to explore caves. Diving is a tool for exploration. If somebody asked me to go diving for pleasure, in the ocean or a reef, I'd say no. I prefer biking, climbing, running. I'm also an instructor of skiing and climbing, I tried paragliding, and I've broken every bone in my body, but in a good way. After one day of sitting around watching TV, I'm completely bored and I have to get moving.

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