In the years since it was first climbed in 1954, it has gained the name "the Savage Mountain" due to the difficulty of ascent and its ugly statistics. For every four people who reach its summit, one dies trying a death rate almost three times that of Mt Everest.
New Zealanders Marty Schmidt and his son Denali are the latest fatalities, killed by an avalanche that swept Camp 3 at 7400m on July 26 or 27. They were part of a team of three climbing the Abruzzi Spur route that ascends the southeast ridge. They were self-reliant, each lugging 100m of rope for fixing high on the peak. Of the seven teams on the route, only they and a Swiss party did not use either Sherpas or high-altitude porters.
See photos from Marty and Denali Schmidt's tragic attempt to summit K2.
Everyone on the route but the Schmidts chose not to press on to Camp 3 because of a perception of heightened avalanche danger. The geography at Camp 3 makes it particularly vulnerable. The narrow valley between K2 and another 8000m giant, Broad Peak, acts as a wind funnel, making the slopes above the camp prone to avalanches when it blows. So much so that climbers often stash extra tents, sleeping bags and food on the Black Pyramid below, in case their camp is destroyed.
The third member of the Schmidts' party, Australian Chris Warner, was to have gone with them to Camp 3 but changed his mind during the night.
Warner spoke to the Herald after his return to Canberra from Pakistan this week and allowed the Herald to quote from an account he wrote to give family and friends an understanding of what happened.
Warner, 35, a climber with 18 years' experience, met Marty, 53, in 2004 on another Himalayan Peak, Cho Oyu, the world's sixth highest. They were in separate parties then but stayed in contact and planned this attempt on K2 together. It was the first time Warner had climbed with Schmidt and the first time he'd met Denali, 25. It was Warner's second attempt on K2.
Marty Schmidt had K2 history too. His first climb on an 8000m peak was on this mountain and route in 1992 with Kiwis Gary Ball and Rob Hall, a climb that resulted in the rescue of Ball from 8300m and the death of a Mexican team member. Ball and Hall died during later expeditions.
"He was definitely well-regarded," Warner says of Marty, a Californian who moved to New Zealand in 1998, a guide of 35 years, including on Everest, who worked for a company that had never lost a client.
"He was primarily known for his guiding. He is a good 8000m climber and that's where he got his reputation."
Both men have stood on top of Everest, Schmidt twice, the last time in May when he guided clients to the summit. Guiding duties done, he was free to return to the mountain Schmidt most respected. "I've been on it twice without summiting," Schmidt said in a press release before departure. "I'm just called to it all the time. That's why I'm filming the 2014 expedition. I want to show the world what it's like. It's like going to the moon without a Nasa rocket."
He was excited to be climbing again with his son, named after the highest peak in North America. "I love to climb with Denali. We have a great time for three months. Not many fathers get that kind of time with their grown-up sons."
Warner, who sometimes slips into the present tense when talking about the Schmidts, says they were "positive, happy people".
"It was a pleasure to climb with them and it was very easy to climb with them. No arguments. It was very peaceful, very straightforward. Denali was new to 8000m mountains but not to big mountains and we all climbed quite happily. We didn't feel stretched at all. And we were very motivated.
"If you are not being guided, making decisions is a big part of being a climber," Warner says about why he changed his mind.
"That means not just following the senior climber, which was Marty. It's easy to fall into line with what Marty says because he's the older, senior guy. So [their deaths] reconfirms my feeling that you have got to make your own decision, whether you go up or down. To me, it's almost like a fight with your ego because your ego is telling you to go up and not to give in. Are you going up because of your ego, or are you going up because the conditions are good and right? I didn't see the great advantage in going up, so I went down."
Warner says it's been suggested that Marty was motivated to press on because of his age but he notes that it was not Schmidt's last chance. He was planning two more attempts by a different route in the next 12 months.
Denali, Warner believes, made his own decision to press on to Camp 3.
"He wasn't pushed by his father, he wasn't convinced by his father. He wanted to go."
Their expedition started with a long walk to base camp through spectacular scenery, a benefit to fitness and acclimatisation. Schmidt senior was justly famous for his energy and enthusiasm. "He's hyperactive," says Warner. "With Marty you are on the move a lot. He didn't sit still. He's just full of energy, and he climbs fast.
"Denali was exactly the same. Not as hyperactive, but he had the physical attributes. He was strong, very strong at altitude. He had his father's legs, lungs and heart. It was inspiring to watch an 8000m novice climb with such ease."
They climbed the neighbouring 8056m giant Broad Peak for high-altitude acclimatisation and, after helping in an unsuccessful rescue of three climbers on that peak, turned their focus to K2. A weather window presented that could enable them to reach the summit on July 28.
Warner takes up the story in his written account: "We left for Camp 2 early on July 25, reaching there just after midday. We were ... packed for a single push to the summit, carrying just four days' [worth] of food and one tent. We all felt strong, healthy and acclimatised.
"That evening as we sat cooking and resting in our tent we heard word that the Sherpas from other teams had failed to make Camp 3 by only a few hundred metres due to the snow conditions. It had been snowing lightly all afternoon and we got different reports of snow being 1.8m deep, chest-deep and waist-deep. The Sherpas had tried to push through the snow but after small sluffs [loose snow avalanches] came down on them and one Sherpa slid down 10m, they decided that it was too dangerous with all this snow sitting on a 30 degree slope of curving blue ice.
"Before we knew it, many teams started descending past our tent, cancelling their summit bid and their expedition altogether. We had only just got on the mountain and everyone was bailing with very little discussion. All three of us were surprised.
"Marty was encouraging people to stay and wait at Camp 2, to let the snow settle. Some agreed but they descended anyway. That night we decided that we all would go up and just see how conditions really were. It was good fitness and acclimatisation and we could make a gear deposit and try again in a few weeks if need be.
"By morning I had changed my mind. It had snowed lightly most of the night and everyone else was descending, so I didn't believe that the three of us could make trail to the summit in such snow. I felt it was better to simply descend and rest, then wait for the next weather window rather than push into new snow.
"Marty and Denali didn't flinch. They said okay to my decision but were adamant about continuing up. We sorted the gear again as they were going lighter in loads, reducing the food to two days ... Both Marty and Denali were in the same frame of mind. One did not convince the other to go up, they were both motivated and prepared to assess the conditions and turn around if need be. So at around 9am on the 26th I swallowed my ego and descended from Camp 2, feeling that I had blown my summit chance as these two were heading to the top.
"I arrived back at base camp that day and waited eagerly for their radio call. By 6.45 they radioed in. They had taken nine hours to reach Camp 3. Marty was brief. He said it had been a hard day, that it was very windy with spindrift [windblown fine-grained snow] and that they were cold. He congratulated Denali, as he had broken trail to Camp 3 pushing through waist-deep snow to 7200m.
"I asked what their plans were for the next day and he replied that he was unsure and that he would let me know in the morning with the 8am radio call. From base camp we could see the wind blowing at Camp 3 and the spindrift coming off the shoulder. My feeling was that they would descend the next day.
"Base camp was now getting divided as the Schmidts had made Camp 3 and some climbers were trying to rally a group to head back up and summit in August, but this met with mixed feelings.
"In the morning of July 27, several climbers came to hear Marty's decision, but 8am came and went. Why hadn't he called? Marty is very good with radio calls and rarely late. We waited and before long it was noon, time for the next radio call. Again, nothing. Had he run out of battery? Dropped the radio, his pack? We're they descending? ... 6pm came and still the radio was silent. We knew they were strong, capable and not the type to make bad decisions. We hoped they were going to walk into base camp any moment. I slept with my radio on, hoping.
"The next day some some Sherpas and high-altitude porters were heading up to Camps 1 and 2 to collect equipment. Getting to Camp 2 was no worry in the current snow conditions as it had only been snowing higher up. Sherpas Mingma and Norbu were heading up to a deposit halfway between Camps 2 and 3 to retrieve an oxygen mask and a few other things. I talked with their leader and convinced them to continue all the way to Camp 3. There were now many climbers low on the mountain, keeping a lookout for Marty and Denali. If they were moving they would be found.
"The Sherpas climbed very quickly and by about 6.30pm Mingma had reached Camp 3. He radioed that there had been a very large avalanche with a scar about 400m wide. He found an axe and crampons that matched the type both Marty and Denali had been using. There was no sign of them or their tent. It was getting dark and Mingma said he felt scared because of the conditions. He took a few pictures and started descending.
"I believe that they would have been in their tent, asleep, when it happened.
"A few days later I made a plaque and we had a gathering at the Gilkey Memorial near K2 base camp. All the climbers came to pay their respects.
For days I still felt they would walk into camp. It just seemed so unreal that they had gone. It was only on the walk out that it began to sink in. The emotions filled my body. I stared a long time at that mountain; Marty and Denali resting high on the ridge.
"It was wonderful to have shared time with them in the mountains; to have experienced such a beautiful relationship: father and son."
A memorial service in New Zealand for the Schmidts is planned for early December. A celebration of the life of Jamie Vinton-Boot, who last weekend fell to his death in the Remarkables Range after a small avalanche knocked him off his feet, will be held at 1pm tomorrow at Wigram Airforce Museum, Christchurch. Vinton-Boot was the 2012 New Zealand Mountaineer of the Year. For more information contact the NZ Alpine Club.