Spanish mountain runner Kilian Jornet has just set a new record time for the ascent, and descent, of 6,186m Denali.
According to Maureen McLaughlin, Public Information Officer for the Talkeetna Ranger Station, Jornet made the round trip ascent from Kahiltna Base Camp in a remarkable 11 hours and 40 minutes.
Jornet planned to spend a month on the mountain, familiarizing himself with the route and acclimatizing for the record attempt. He carried skis on the climb but other details are not yet known.
In 2003 American Chad Kellogg became the first known person to climb and descend the mountain in under 24 hours.
Following the standard West Buttress Route, Kellogg reached the summit from Kahiltna Base Camp in 14 hours and 22 minutes, returning in a total time of 23 hours 55 minutes.
This is a total distance of around 53km, with a height gain of ca 4,000m.
The well-known Alaskan guide Vern Tejas tried to reduce the time in 2009, but it had to wait until last year, when Ed Warren from the US Air Force, reached the summit in 12 hours and 29 minutes, and descended in four hours and 17 minutes, a total of 16 hours and 46 minutes.
Warren skied roped with a friend up the initial crevassed glacier as far as Ski Hill, then continued alone, his friend waiting for his return.
Warren reportedly had only nine days of acclimatization, and used ski boots throughout, while Kellogg and Tejas had partly worn running shoes.
Jornet's round trip time on the West Buttress from Kahiltna was faster than Warren's ascent, and the Spanish climber now plans to continue with attempts at speed ascents of Elbrus (already tried last year), Aconcagua, and of course Everest.
In August 2013 Jornet set a new speed record on the Matterhorm by climbing from Breuil up the Italian Ridge to the summit and down again to Breuil in just two hours and 52 minutes. This was more than 20 minutes faster than the previous record set in 1995 by the Italian Bruno Brunod.
The previous month he had already set the record for Mt Blanc from the church in Chamonix, ascending and descending the Grands Mulets Route in a total of four hours and 57 minutes. For much of this time he wore only running shoes, shorts and a T-shirt.
But Jornet's promotion of "light and fast" in the mountains has been heavily criticised by some members of the Chamonix Valley climbing community. They point out the lack of any safety margin, and a reliance on the immediate assistance of the highly talented PGHM rescue team.
Jornet himself was attempting a rapid ascent of the Frendo Spur on the Aiguille du Midi with fellow mountain runner Emelie Forsberg, both lightly clad and in mountain running shoes and crampons, when they got into difficulty near the top.
The weather closed in while they were trying to find the exit, and Forsberg got so cold the pair had to call for a rescue. Unable to use the helicopter due to poor visibility, the PGHM team rappelled from the top of the route and evacuated them.