A pair of Russian divers reached a record depth underneath ice just outside the Arctic Circle on Saturday. The frigid temperatures and intense pressure made for extreme conditions.

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Maxim Astakhov and Alexander Gubin are professional scuba divers who work for the Russian Geographical Society. Their dive over the weekend was both a record-breaking attempt, and an opportunity to truly put new diving equipment to the test, Russia Today reported.

The duo, saddled with multiple air tanks, reached 102 meters — about 335 feet — under the icy surface of the White Sea just outside the Arctic Circle. The record was confirmed by Bojana Ostojic, a logistics expert who was a longtime member of Jacques Cousteau’s team as well as a member of the Russian Geographical Society and a World Underwater Federation associate.

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“At a depth of 100 meters my gloves tightened so much it felt like I was going to see my nails,” diver Alexander Gubin told Russia Today. “My hands felt terribly cold.” No surprise there. The salt keeps that water liquid even though its temperature is actually below freezing, the Guardian pointed out.

RT via Youtube

While other divers have gone deeper in Antarctica, this 80-minute dive was the deepest one under a hole in ice, according to UPI. Going after cold water records is nothing new for the Russian Geographical Society. In early 2013, their team reached the bottom of Labynkyr Lake in Siberia, one of the coldest lakes on the planet. And last summer their divers reached 111 meters (364 feet) in the Arctic.

For context, Astakhov and Gubin went more than twice the normal depth limit of bottlenose dolphins and qualified divers — to a depth greater than the height of Big Ben, the Guardian’s infographic shows. Watch the daring dive here:

Diving through a hole in thick ice makes a terrifying difference since it can contribute to disorientation underwater. Plus, the pressure and temperature can cause equipment to fail, Atlas Obscura’s Jessie Guy-Ryan noted.

Although the Russians appear to be calm in the video amid all the test tanks, things didn’t go exactly as planned. The Guardian reported that, after he emerges, one of the divers says his equipment took a while to start working properly in the extreme conditions. Yikes. But clearly a bit of wonky equipment and mind-numbing cold isn’t going to slow these guys down.