Oh, the absolute lethargy of 24,600'. You want to pee, and you lie there for a quarter of an hour making up your mind to look for the pee bottle. The South Col Route Mouse over the climbing route for info and click to see a photo from that spot on Everest. Above 26,000' there's about a third of the oxygen available at sea level. Even acclimated, the body begins to shut down, and if a person stays that high long enough, they will die.
Most climbers use oxygen here for climbing and sleeping.
Neither has ever said who stepped on the summit first. It is unknown if they reached the summit before disappearing. In 1921, Mallory had led the first ever expedition to Everest.