'Unearthly': Russian free diver Alexey Molchanov speaks out after record-breaking ice dive Alexey Molchanov dived under the frozen waters of a quarry in Moscow

MOSCOW -- Free diver Alexey Molchanov -- the son of famed Russian free diver Natalia Molchanova -- is no stranger to death-defying feats.

He has held his breath under water for an eye-popping 8 minutes and 30 seconds (a far cry from the world record of 24 minutes!) and dove 426 feet into the ocean.

So when he set his latest world record this week-- swimming an excruciating 181 meters (nearly 600 feet) under solid ice in the frigid waters of a quarry near Moscow— it was one of the easier things he’s done, while still being a superhuman challenge.

“I didn’t want to push it,” Molchanov told ABC News a day after he set the record for the longest dive under ice, beating the previous record set by the French free diver, Arthur Guérin-Boëri, who swam for 175 meters in 2017.

Molchanov said he felt he could have gone further but didn’t want to risk it because despite hundreds of dives in warm waters, doing it ice is something quite different.

"Free diving under ice, it’s harder to be sure," Molchanov told ABC News at a Moscow swimming pool, where he was training again after the dive.

"In the cold water you burn oxygen much faster than in warm water. So for me 2 minutes 40 was already very hard."

Free diving is the extreme sport where athletes dive to remarkable depths without scuba gear or additional oxygen supply, instead only holding their breath, usually for several minutes at a time.

The sport is difficult and dangerous even in the warm waters where it is usually practiced, but in Russia a small number of divers also free dive under ice.

Molchanov on Tuesday swam between two holes cut into several inches-thick ice at the quarry, wearing a monofin and a wetsuit to protect him against the frigid water that was around 35 degrees Fahrenheit.

He held his breath for about 2-1/2 minutes, gliding through the murky green water, where visibility was around 3 to 4 meters. The record was registered by a judge from the world free diving body, the International Association for the Development of Apnea (AIDA). The achievement will now be added to the Guinness Book of World Records, which is currently processing it, according to a spokeswoman for Molchanov.

The challenges of regular free diving are multiplied under ice. The freezing water makes it harder for the diver to achieve the relaxed state needed for holding their breath. It can also be dangerous, because the ice above means there is no way out except the small holes cut into it should they become disoriented.

Usually divers tether themselves to a rope to avoid drifting away from the holes, but on Tuesday Molchanov was unattached, just following the line.

"I know if I lose the rope the guiding rope, I can be lost under the ice and it’s a really, really risky situation,” he said.

Molchanov is the son of Natalia Molchanova, the world’s most famous free diver, who vanished while diving in Spain in 2015 and is presumed dead.

Molchanov said he had chosen to try the record now to coincide with the premiere of a Russian feature film based on his mother's life, called One Breath, on which he consulted. The quarry where he completed the record dive was also used as a location in the movie.

Few free divers do under-ice diving, with most usually travelling to locations like the Red Sea or the Maldives. Those that do ice dive are mostly Russian. In 2015, ABC News filmed with a group of free divers diving in the White Sea in the Russian Arctic, attracted by what they said is the unique sensation being cut off from the surface creates.

Molchanov already holds a number of free diving world records, including the deepest dive with fins and constant weight when he dived 130 meters in the Bahamas in 2018 (for comparison London’s Big Ben is 93 meters tall). He said that he now intends to try to break more records, perhaps including a depth dive at Russia's Lake Baikal. the world's deepest lake.

He said he was also considering trying to repeat another distance dive, but this time without a wet suit….