10h14m – Jack Kuenzle Sets ‘Fastest Known Time’ For Ascent/Descent of 20,310′ Mount Denali, AK

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jack kuenzle
Jack Kuenzle. Credit: Jack Kuenzle

On June 5th, 2023, Jack Kuenzle of Roxbury, CT, set a Fastest Known Time (FKT) for ascending and descending Mount Denali, AK. Kuenzle, a former Navy Seal, an ultrarunner, and an endurance coach, climbed from base camp at 7,200′ to the summit of Denali, and back down, in 10 hours and 14 minutes.

“10:14:57 Round trip on Denali from the airstrip. 34 miles 14,000 ft of climbing. The most full on thing I have ever raced.”

– Jack Kuenzle

Kuenzle combined skiing and skinning to complete the 34-mile round trip with 14,500 feet of climbing beating the previous record by more than an hour.


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Karl Egloff, an Ecuadorian/Swiss climber, set the previous record in 2019 at 11 hours, 44 minutes, narrowly beating Kilian Jornet’s time of 11 hours and 45 minutes by one minute, although Jornet used skis while Egloff didn’t. From base to peak on land, Denali stands at 20,310 feet, actually making it the world’s tallest mountain by that measurement.

Kuenzle is no stranger to bagging FKTs, he has twenty worldwide. These range from the fastest ascent of Mt Shasta, CA, in the USA, the insane Bob Graham Round in the UK (where he beat Kilian Jornet’s FKT), to four round trips in Bosnia and Herzegovina.

Meredith Edwards, a US mountain endurance athlete and member of Team Vibram, is also currently on Denali for her FKT attempt.

Route map.

The trip in his own words:

Bulls on Parade

Previous RT record: Karl Egloff 11:44

Previous RT record this style (no fixed lines, only water at 14 for support): Kilian Jornet 11:48

I just want to acknowledge Kilian’s effort. The two efforts aren’t terribly comparable, I have heard stories of how horrendous the weather was the day Kilian did it. This is an effort that is enormously affected by conditions and is slower and certainly fatal if you race on an adverse day. Kilian sent this in perfect style and set a great precedent going forward and his effort guided and inspired mine own on the route. Further, tactics and gear have evolved a lot since 2014. It just bothers me when someone sees an FKT and treats it like a same day race head to head. Yes my effort was 90?? Minutes faster than Kilian, but I am in no way 90 minutes faster than him on this terrain. Just want to make that clear.

Left Colorado on like 22 May and spent that night and the next two at sea level. Had been sleeping at 8600 since start of December, 10000-12000 since mid April. May 24 we had our ranger brief and attempted to fly out that day but weather prevented. I almost tried to rent a Hypoxico, it’s not uncommon for climbers to be stuck in talkeetna for a week or more waiting on weather. Landed on the mountain May 25th. Slept at 8900 that night, 11 camp the following, and then at 14. The movement from the airstrip to 14 was brutal. Typical to carry weight in a large pack and a sled, at least to 11k. I wanted to have a ton of margin on gear and food such that I could focus on the record. When we weighed out at Talkeetna air, we had 335 pounds of food and gear, with no water or fuel. We lost a bit to a cache at the airstrip, but I wouldn’t not be surprised if my total carry weight exceeded 200 pounds. We carried everything in a single push to 11K, cached a ton of food, and then double carried in two runs to 14. This strategy is extremely aggressive.

This year in particular many folks were plagued by problems acclimitizing, multiple experienced climbers had to be heli’d out of 14 camp due to HAPE/HACE and one even died from it. He lived above 5000 ft. My partner, Zach McCarthy began experiencing some issues with altitude after our first night at 14. Headache, nausea, confusion…it started to look like HACE so we took him down to 11 camp (a very dangerous movement across some cracks near windy corner in itself, 0 vis, 0 track and zach was probably not in a state where he could have arrested my fall in a crevasse). He slept there two nights, didn’t improve, so I took him to the airstrip and he flew out.

Generally the route is as follows. From the airstrip, you go down 500 feet. You then travel up about 1000 ft over the next five miles of glacier travel to camp 1. Later in June and in low snow years, this lower glacier becomes more treacherous (from a crevasse fall perspective) and the route becomes much less direct as it has to seek out strong snow bridges and end run other crevasses. So this section is fastest early season or in really fat years (like this year, at least below 11). This year was so fat you could only see a couple of open crevasses total that existed within 50 yards of the track.

After Camp 1, the route angles up and probably averages 20-25 degrees up to 9600 ft. This terrain skis quite well although it can be sun affected. 9600-10500 is a sneaker crux. The terrain is pretty low angle and even flat which makes a bit annoying on the down. Further, it’s subject to some of the worst weather on the mountain. Only twice did I go through this stretch with visibility greater than 10 meters (record day descent and day after ascent). A smaller, bit steeper hill leads to 11 camp.

11 Camp is at the base of motorcycle hill, a 500 ft 25-30 degree hill that has fair potential for crevasse fall. Of the folks I heard of falling in crevasses, almost all were on this hill. After motorcycle is squirrel hill, a lower angle 800 ft hill above a massive (fatal) drop to the Peters Glacier. In good powder, as Nathan and I skied it a week before the record, this thing is trivial. During the record, I encountered it as a thin strip of edgeable wind board flanked by blue ice. Truly horrifying while carrying a heavy sled. Above squirrel is about a half mile of super low angle, even flat terrain to the base of a 600 ft, 25 degree hill up to Windy Corner. Windy Corner features a flat, narrow side hill traverse on hard snow or blue ice above some big crevasses. Typically I was doing crampons here if I had weight, I could edge it on skis and skins if I was slick.

Above WC there is a brief section of crevasse navigation, probably the highest potential for deadly crevasse fall on the normal West Buttress route is here. It’s trivial if there is a track but can be a bit confusing if you have to establish a route. Low angle terrain leads up to 14 camp. From 14 camp, the route follows 30-35 degree terrain up about 1600 ft. From here, I diverted for the rescue gully variation, which takes a more direct line up to 17k camp. It’s all booting from 15600-17100 and terrain ranges from 35 to high 40’s. There are a number of crevasse crossings here, but the terrain is steep enough the danger is a bit mitigated.

After topping out RG and rejoining the traditional WB line, the route drops about 100 ft to the autobahn. The autobahn is the site of the most fatalities on the mountain, it’s a long, low angle slowly rising traverse from 17000-18200 and denali pass. It’s very exposed, a fall at the Denali pass end of the traverse would almost certainly be fatal. Many protect it using fixed pickets maintained by the NPS. Obvi if you are skiing this section these present more of an obstacle than a point of safety.

Above Denali Pass, the route is generally low angle as it heads up to the summit knob (Kahiltna Horn). The actual summit is steeper than I expected. You summit the lookers right side of the horn and then have to do an extremely exposed ridge traverse about 100 yards to the actual summit.

After arriving at 14 camp, I had three objectives:

-see the upper mountain
-establish a safe and fast way up rescue gully

Rescue gully gets some traffic, but probably only 5% of that versus the fixed lines on the traditional WB. Weather and assisting Zach hampered the first couple days trying to get into RG, on Friday (I raced Monday) Nathan and I were able to boot it but I felt our route was pretty unsafe from a crevasse fall perspective. On Saturday I resolved to probe and wand a safer route, but I ran out of wands and time when weather rolled in. I found a safe, direct line but only to 16,200 and resolved to go up during better conditions Sunday. Sunday I got up and the forecast looked great for Monday. Further, the Sunday forecast was marginal and I felt some folks would go to the summit and start to put in a booter. I tried to find someone in camp to put in an RG booter (including offering to pay people quite a bit), but people come to the Alaska range to do their own projects on the good weather days. Suddenly I looked up into RG around noon and 3 people were booting it. Once they got above 16,200, I committed and packed an overnight kit and skied down to the airstrip. The only unfortunate surprise was WC and squirrel, which I expected to be blower pow and were instead wind hammered snow strips flanked by blue ice. Oh and I broke my Scarpa Aliens, for the 15,000th time the screws walked out/stripped out of the walk ski mode lever. With one boot permanently in walk mode, I skied slowly down to the airstrip with a pack. There I made dinner, had an absolute cluster fuck of a time figuring out how to pitch my friends bivy tent, and went to bed.

I felt the best conditions on the route would be cloudy below 14 and sunny above, and Monday dawned basically just that. Cloudy below would keep me cool on the ascent and prevent the descent from getting too soft, slow, and sloppy and reduce the chance of crevasse fall on the lower glacier. I carried with the following (x indicating if I used it):

-28l pack x
-hybrid steel aluminum crampons (ankle keeper removed for transition speed) x
-race straight axe x
-running belt with 1L water x
-additional 1L water on chest x
-carbon race poles x
-65mm race skis x
-4000 calories in primarily drink mix but also some gels, nutrition for 14 ascent and 14 descent in different bags x
-Teague Holmes high speed kicker skins x
-full coverage skins
-lightweight bikini over boot
-big puffy jacket x
-down full zip shorts
-rain jacket and pants
-heated socks x
-heated 3/4 tights x
-puffy down mittens x
-sunglasses x
-helmet x
-merino buff with mouth hole cut through and sewn
-grid fleece hoody x
-inreach x

In the past, there has been no agreed upon start for this route. The glacier airstrip has some structures that are permanent for the length of the season but no landmarks that are truly permanent. I meant to pull a lat long but I think it should just be standardized to where I started, the location of the airfield managers tent in 2023.

I skied sans skins down heart break and to the glacier. Put the kickers on and skinned across to camp 1. An inch or two had fallen overnight but the great thing about skinning this route is all the sled traffic creates a wide track perfect for skinning. 9600 things took a turn, the ever shit weather of Kahiltna pass was in full effect, blowing snow and the track was completely filled in. I was postholing a foot deep or more for the very low angle section to 10500. Vis was so bad I had to load a gpx on my watch and follow it, constantly probing for the buried track. Just before 11 things improved. While I have skinned from 11 to 14, the wind stripping meant I had to switch to booting midway up motorcycle and until the top of squirrel. Skinned polo fields and wc no problem. Polo fields I got first look at the upper mountain, a massive angry lenticular was pegged above 17k. I kept thinking of George in Seinfeld going “the sea was angry that day my friends”. It looked horrendous up there but I resolved to continue until I had to turn around. At 13,500 I caught sight of 3 climbers booting rescue gully and almost started crying I was so happy, meant the booter and skinner would be freshed up. At 14, Emanuel Rohss had put out water for me, but I drank the couple liters staged and needed more and saw Alex king and yelled to him and he ran water over to me. Grabbed like 3 liters? For upper mountain.

Started skinning and from the start the skinner was insane. I’ve never seen a skinner so perfect idk how tf they made it. Skinned all the way to 15,500 crevasse below RG. I found the kick turns really stressful at the altitude, just the core engagement on the steep terrain would wipe me out for a bit.

When I got to the booter I was a bit confused, it was almost all filled in. I booted up and eventually realized that there was just so much spindrift and wind action the booter was almost immediately refilling. If they hadn’t have booted it right before me, I would have been postholing the whole way up, would have added a lot of time. One of the dudes booting fell in a crevasse so that also would have been an issue, although I was a bit more familiar with the terrain than them. The whole day I hadn’t added any clothing, I took my top off on the lower glacier and had replaced it at 9600. 3/4 tights and heated socks turned off on the bottom. On this booter I was roasting, the greenhouse was in full effect and it was so hot.

Once I got to 17 I was entering uncharted territory (for me). At first I was on the autobahn and couldn’t figure out how someone would kill themselves falling, it just wasn’t very exposed. By the time I got to Denali pass and had traversed up 1200 feet over a drop that was simultaneously falling away I was very concerned about skiing. Especially given how firm it was. Not icy but the firmest windboard id ever seen. Whole mountain above 17 was like this, that video Alex Mitchko took of me skiing was the only good turns above 17.

Above 17 the weather was absolutely splitter. Barely a breath of wind and I was comfortable in my hoody tights and mittens. Tons of other climbers were on the route and chasing, passing, and chatting with them was a huge boost and broke up the climb really well. Pretty uneventful to the football field (flat stretch before kahiltna horn/summit knob). Upon seeing the horn I was shocked how steep it was. One thing that’s tricky about the terrain above 17 is it’s very different from anything I’ve seen in lower 48. It’s like incredibly steep and wind shaped snow, with wild vertical 4+ foot wind lips all over the place. I became very concerned I’d pick a shit line and get cliffed out by one of these. Somewhere around 19 my water and food consumption dramatically fell off. Up to this point I’d been pretty disciplined but I think I didn’t eat or drink much between there and finish.

I was feeling super addled by the altitude at this point. I’d never been this high, only up to 17k one time before. I was purse lip breathing like crazy and that was helping. I felt my judgement was being a bit affected and didn’t feel comfortable doing some wazoo route finding. I reached the summit ridge and was a bit concerned by how exposed the ridge was, a fall to the south face would absolutely be fatal, a fall towards the route and the football field would not be pleasant. On the summit ridge, I decided my focus for the rest of route would just be on not killing myself and time wouldn’t be much of a thought. Just before the summit I thought fuck the uphill split and stopped and unpacked my big jacket and put it on. I ran out and tagged the summit and quickly decided just to run back and ski directly down the route, instead of attempting to figure out a line on lead going down the horn.

The skiing was absolute garbage and slow af. I tried to build some speed to carry up the 100 ft slope on the far side of the football field but couldn’t, I took my skis off and walked up dragging them and my poles like a petulant child at a ski resort. Uneventful to Denali pass. At the autobahn, I was concerned about the firm snow and exposure but it ended up going fine. At rescue, the top 600 ft was very firm and wind scoured. I started hop turning and then thought better and just side slipped the top 1000 ft. Style out the window.

Navigating the crevasses and slope down to 14 camp the snow was deep and heavy hot pow and I had to stop a couple of times to rest. Visibility was near zero due to fog. Just below 14 I was able to really open it up and hit like 35 going into wc which was a little rowdy on the skimo setup. Down at squirrel things were super firm and so icy but the slope is so low angle I don’t think there was much danger. There was a guided group there I had to dodge and weave through, albeit very slowly. I was very concerned, almost convinced, that, like Shasta, I would break my skis on the ice. Fortunately I didn’t.

Motorcycle skied fine. From 11 to heartbreak I just pinned it in the sled luge track as fast as I could, double poling like crazy whenever I had to. At base of heartbreak I threw the kicker skins back on and skinned up as fast as I could.

After chatting with a couple people on the finish, I went back to my tent and made some shit dehydrated meals and went to bed. I woke up like six hours later and then started an absolute torturous epic back up to 14 to breakdown camp and pack out our hundreds of pounds of gear to the airstrip. Took 6 hours up and 8 hours down, I got back at 5:00 the next morning. Just horrendous. The after math to this effort has been so dog shit it’s unbelievable, shit sleep, long slogs, and horrifically chapped and sun burned lips. Almost made it all not worth it ha ha kinda serious

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