British adventurer Lewis Gordon Pugh has taken on his own world record for the longest ice swim by swimming in sub-zero temperatures in a northern Norwegian lake.
BBC News correspondent Robert Hall watched the man, known as the Ice Bear, take the plunge in a freezing fjord.
A towering glacier, and a frozen lake, perfect conditions for a dip. At least if your name is Lewis Gordon Pugh.
He's already swum in the Arctic and the
Antarctic, but this was the most ambitious plan yet - a 1.2km swim would take him well over 20 minutes.
Dressed only in trunks, swim cap and goggles, this would be the longest swim in near freezing conditions.
The day before the attempt, Lewis took me to the torrent that pours from the melting glacier.
I could hold my hand under water for barely 30 seconds.
Scientists who have studied the swimmer's previous attempts believe he has the ability, either consciously, or unconsciously, to raise the core temperature of his body in the minutes before he enters the water.
It's just enough to slow the effects of extreme cold, but not enough to prevent extreme discomfort.
"At first you can hardly breathe because of the shock," Lewis told me.
"Then the cold attacks your skin, and as the time passes, it seems to move right into the core of your body."
Today a crowd of villagers and schoolchildren had gathered to watch this example of English courage, or lunacy.
Lewis didn't hesitate, ploughing straight into the lake.
As the minutes ticked by, sensors attached to his body showed his temperature dropping but, yard by yard, he swam on.
Eventually, after 23 minutes, it was over.
Lewis was helped ashore to be told his record had tumbled, but that he was, by now, suffering hypothermia.
Rushed by boat and car to the bliss of a warm shower he suffered no ill-effects but as he gazed at the glacier he said he had probably reached his limits.
The event has provided science with more data on our ability to survive extreme temperatures.
And it has provided Lewis with good reason to stick to balmier waters, at least until someone challenges his new record.