Diemberger was one of only two survivors in the 1986 K2 Disaster. On 4 August 1986, Diemberger and Julie Tullis reached the summit of K2 very late in the day. Shortly after starting their descent, Tullis fell and dragged Diemberger down with her. They somehow stopped from going over the edge and spent the night above 8,000 metres. They managed to reach Camp IV the next day, where they were forced to share two tents with six other climbers after their tent had collapsed from hurricane force winds. Tullis died later that night, possibly from high altitude cerebral edema, and only one other climber, Austrian Willi Bauer, survived the descent with Diemberger. Both climbers suffered severe frostbite during the descent and had to have amputations.