Everest may get the headlines, but for veteran mountaineers, reaching the top of K2 and coming down alive is the dream.
Located on the Chinese border with Pakistan, it was first scaled in 1954 by two Italians -- Lino Lacedelli and Achille Compagnoni. There have been around 280 summits of the 8,611m peak in the Himalayas since then.
Everest, on the other hand, is just 237m higher but has been summitted more than 2,000 times.
That is because K2 is the among the three hardest climbs in the world, with surrounding weather that is significantly colder and less predictable than on Everest, and its dark grey rock significantly more difficult to scale.
K2 is also known as the "killer mountain" because of its attrition rate. Before this weekend's tragic events, some 66 climbers had died on K2. Its overall summit/fatality rate of 23pc is the third most deadly mountain in the world. Only Nanga Parbat and Annapurna in the Himalayas are deadlier.
Only six women have ever reached the top, but three died on the descent.