Only a few seconds in the icy depths would be enough to kill most mere mortals. But yesterday, protected by nothing more than a pair of Speedo trunks and his extraordinary central heating, Lewis Pugh took the plunge and became the first man to swim at the North Pole.
The 36-year-old Londoner spent almost 19 minutes at minus 1.8C as he front crawled for a full kilometre – more than half a mile in the coldest water a human has ever swum.
It was like jumping into a dark black hole,” he said. “The pain was immediate and felt like my body was on fire.
“I was in excruciating pain from beginning to end and I nearly quit on a few occasions. It was without doubt the hardest swim of my life.”
But he said that a colleague ski-ing on pack ice alongside him looking out for hungry polar bears spurred him on.
To develop his cold sea swimming technique he practised in a pool filled every day with a ton and a half of ice.
He has broken more than 20 endurance swimming records which include the first swim of more than 1km in the Antarctic Ocean.