Kiwi snowboarder Chris Dunn is no stranger to high altitudes, but will be in unfamiliar territory when he competes in a 60km ultra marathon in the Himalayas.
Mr Dunn will run the Tenzing Hillary Everest Marathon, an annual event which starts at Everest Base Camp, at an altitude of 5400m. The race takes runners downhill, finishing at an altitude of 3400m.
As well as the standard 42km race, this year a one-off 60km "extreme" marathon was added to the event to mark the 60th anniversary of Sir Edmund and Tenzing Norgay's Everest summit.
Speaking from Kathmandu this morning (Wed), Mr Dunn, 27, said he decided to enter the run six months ago, and ran his first 50km ultra marathon just last month.
A former Sir Edmund Hillary scholar at Waikato University, Mr Dunn is being supported by the university on the trip.
"I've always wanted to come to base camp. I thought this would be an awesome extra thing to do while I'm here," he said.
"It's seeing how Sir Edmund did it and getting a little bit of an insight into his journey."
He was also interested to meet and talk to climbers at base camp about their experiences on Everest.
As well as long-distance running, Mr Dunn has been working out at an altitude training centre, which simulates the effect of altitude by wearing a mask which restricts oxygen.
"They're used to training triathletes to perform better at sea-level, so when I went there and said I was doing this marathon at altitude they were a bit blown away and had to rethink their programme."
He said there was no way to know how he would cope with the conditions until he gets there.
"I'm not 100 per cent sure how my body will react to that altitude, so I'll just have to wait and see."
Mr Dunn said he would expect to run 60km at sea level in about six hours, but was preparing for a much longer race from Everest.
"It's going to add on at least an hour but probably more like two hours to my time.
"That's still providing I get to the actual start-line as well."
Before starting the race on May 29, competitors will trek together for two weeks to reach base camp.
After the marathon they'll trek back down to the sloping mountain air strip at Lukla, before flying to Kathmandu.