From climbing the frozen Niagara Falls to setting world paragliding records, Will Gadd is no stranger to adventure.
Rappelling into a hole to descend deep into the bowels of the Greenland ice cap, however, was a whole different matter.
"Safe is a relative term," laughs the mountaineer based in Canmore, Alta. "These moulins (vertical shafts) are not safe. There are a lot of things that can go wrong.
"But for research, it's worth it."
Gadd has earned a reputation as one of the world's top ice climbers. He has records, prizes, first ascents and personal achievements from around the globe.
Now he's offering his alpine passion and skill to the research community by taking scientists into places they couldn't reach on their own to study the impact of climate change on the high altitudes he loves.
"I've been in the mountains now for so long I've seen them change radically," Gadd said in a recent interview.
"If I'm flying my paraglider over the mountains, all of our glaciers look like they've got a bad case of bathtub rings. You can very graphically see where they were in relatively recent history."
Old maps are wrong. Routes for popular climbs have changed.
"The way we approach the mountains now has to be different," Gadd suggested. "The glaciers are changing so quickly.
"It's not some abstract thing. It's obvious. In our lifetime we're seeing radical changes and it's not something I can ignore."
Gadd had long been climbing into moulins -- holes in glaciers that drain surface water which sometimes carves extensive caves under the ice. Originally, it was just a fun way to ice climb in the summer.
But he grew curious about what was actually down there. He got in touch with a University of Alberta glaciologist and in 2016 the two began descending into the Athabasca Glacier in the Rocky Mountains.
Those expeditions found thin layers of micro-organisms living deep within the ice.
"Next thing you know, I'm involved in all these research projects under the Athabasca Glacier."
Eventually, Gadd contacted U.S. scientist Jason Gulley, who works on the Greenland ice sheet -- 1.7 million square kilometres of ice an average of two kilometres thick. The two worked out a plan to climb 100 metres down into a moulin in the hope of diving once they hit water.
They made their attempt last fall. The ice was too unstable to let them descend as far as planned -- but they still got plenty deep.
"It is one of the coolest places I've ever been in in my life," said Gadd. "It's this whole world that's been sculpted by water in the ice.
"It's just surreal and incredibly beautiful. It's like the beautiful red sandstone slot canyons in Utah, but blue ice. It's a magical world. It feels very alien.
It was challenging, too, he said.
"A lot of times you have to climb on the walls to get over water-filled passages. Who would expect open water at -30 C in a glacier?
"You need a hodgepodge of MacGyver-style trickery to move around in these places. It's all slippery slopes leading to sure death."
Those experiences have marked him.
"I'll never look at a glacier the same way again. I used to think of glaciers as blocks of ice chundering down the mountain, (but) there's life in there and it's like Swiss cheese in there. There's a whole world that you just can't see from the surface."
Gadd is planning to set out Monday on a cross-Canada lecture tour to talk about his work with researchers to understand the changing climate and alpine environment.
Climbing for its own sake is great, he said. But, at 52, he's hoping for something a little more from his prodigious skill set.
"Using some of those skills I've developed in my career to help people move around in the glaciers and further our understanding of the world is a good use," he said.
"It's a small legacy, but if you can make a little bit of a difference, I think that's worthwhile."
