As the newest extreme sport, it is more "Titanic" than Olympic. Ice surfing gives you the chance to dice with death while enjoying the planet's ultimate chill-out.
It is not the easiest of pastimes to enjoy. First you have to find a glacier about to "calve," then wait for up to two weeks for a house-sized iceberg to break off before catching the monstrous wake after it hits the water from 500 feet high.
The reward: Sixty seconds of sheer exhilaration as you ride a 25-foot wall of ice-cold water filled with millions of shards of razor-sharp ice, mud, boulders and debris.
It is a long way from his usual haunt of Hawaii, but pro surfer Keali'i Mamala, 28, has just recorded the world's first one-minute glacial wave surf ride.
He achieved the feat 50 miles inland on the Copper River in Alaska, 2,800 miles from Honolulu.
"It wasn't very big but it got the hairs on the back of my neck tingling," said Mamala. "I felt myself at the barrel's edge. It was a rush but it was a good feeling, all natural and super-powerful."
He and surfing partner Garrett McNamara, 39, adopted their usual method of "tow-in" surfing. McNamara used a jet ski to tow Mamala on his surfboard to the glacier.
The surfers then had to wait for weeks for their chosen glacier to calve. A team of film-makers sent to document their feat packed up their gear and called it a day after two weeks and it was left to a lone photographer, Bo Bridges, to capture the dramatic moment when the ice fell and the surfers rode the tsunami-like wave.
McNamara said: "It's the heaviest thing I have ever done in my life. It's like the Empire State Building about to come down on top of you."
Waves 40 feet high were recorded when the glacier calved in 1993. The waves race across the broad channel before crashing into the opposite river bank, sending geysers of rocks, marine life and trees into the air.
Sometimes the "blast" from the ice hitting the water is so big that hunters find dislodged salmon in the tops of pine trees on the banks of the river.