May 29th

Edmund Hillary and Tenzing Norgay were the first explorers to reach the top of Mount Everest on this day in 1953

At 8848m high, there is only one-third of the oxygen (O₂) at the summit of Everest compared to that at sea level. The two climbers used oxygen gas to help them reach the top, but could only stay for 15 minutes as the oxygen levels ran low.