A British endurance swimmer summoned the peak of his powers to become the first person to swim under the summit of Mt. Everest, Sky News reported Sunday.
Lewis Gordon Pugh battled freezing waters wearing only a pair of Speedos, a cap and goggles to cross the one kilometer (0.62 miles) glacial lake next to the Khumbu Glacier.
But an adapted approach saw him through to complete the swim in a time of 22 minutes and 51seconds.
Pugh has battled ice-cold water before, swimming "with speed and aggression" in Antarctica and across the North Pole.
The 40-year-old earned the nickname the 'Human Polar Bear' for his aptitude in arctic conditions.
He set off for the Everest summit on May 5, almost nine months after announcing the project.
But he quickly learned he needed to take a different approach in the 2C (35.6F) Pumori waters, which he scrambled over rocks and boulders to access.
"You can't use the same tactics," he explained. "Because of the altitude you need to swim very slowly and deliberately.
"Swimming 20 meters at full speed in the test swim, I felt I was going to drown."
He adopted breast-stroke to help his breathing and concentrated all his energies on controlling his speed.
Going too fast could have pushed him into hyperventilation -- too slowly and he would have died of hypothermia.
The environmental campaigner undertook the challenge to raise awareness of the melting glaciers in the Himalayas and the impact of declining water supplies in the region.
"I have seen glaciers in the Arctic, the Alps, Central Africa, Antarctica and the Himalayas -- and it's the same story everywhere," he said.
"Most glaciers are melting away. The glaciers in the Himalayas are not just ice. They are a lifeline -- they provide water to approximately two billion people."
