A trek to base camp at Mount Everest will leave you short of breath in a hurry.
A push to the summit begins in thin air, 17,000 feet above sea level — higher than any peak in the Rocky Mountains. Once you reach the “Death Zone,” above 26,000 feet, oxygen levels drop to a third of what they are at sea level. Few climbers reach the summit, which rises 29,029 feet above sea level, without bottled oxygen.
To acclimate their bodies to diminishing oxygen levels, climbers ascend Mt. Everest i