Denali, formerly named Mount McKinley, is the highest mountain peak in North America and in the United States, with a summit elevation of 20,320 feet (6,194 m) above sea level. Measured base-to-peak, it is the tallest mountain on land. Measured by topographic prominence, it is the third most prominent peak in the world after Mount Everest and Aconcagua. It is the centerpiece of Denali National Park and Preserve. Nelson Dellis climbed this peak in 2009. It was his first expedition-like trip, taking 21 days to climb, summit, and return. It was also his first real test at high-altitude. No problem; he conquered this peak without a hitch. With Everest aspirations in sight, this was a key peak for him to conquer in order to prove he was ready for Everest, which was the first big fundraising effort for Climb For Memory.