#7. Denali, Alaska 6,190 metres (20,310 ft.)
Mt. McKinley, also known as Denali, is the highest mountain in North America. Though its altitude is only 20,320 feet, its high latitude means that the atmosphere is far thinner than it would be at the equator. For the many people who climb Denali each year, the altitude, weather, and extreme temperature pose a serious danger. For these reasons, the success rate on Denali is around 50% and more than 100 climbers have died attempting the summit.