#20: Mount Kilimanjaro, Kilimanjaro National Park, Tanzania
Africa's Highest Mountain
At more than 19,000 feet, Kilimanjaro is perhaps most famous (thanks to Ernest Hemingway) for the snows, or ice cap, on its peak. Since 1910, more than 80 percent of the ice has disappeared and the long-dormant volcanic mountain is expected to be ice-free in the next 10 to 20 years. (Chris Jackson/Getty Images)
A trio of volcanic cones – Mawenzi and Shira, considered extinct by geologists, and Kibo, a dormant volcano that last erupted between 150,000 and 200,000 years ago – makes up what we know today as Mount Kilimanjaro.
Celebrated by Ernest Hemingway in his 1936 short story "The Snows of Kilimanjaro," its 19,336-ft.-high peak has become a mecca for mountain climbers ever since, drawing some 35,000 each year. Though not especially difficult from a technical perspective – no ropes, harnesses or ice crampons are required – the climb tests the limits of human endurance, as many attempts have to be cut short due to altitude sickness.
While dormant, Kilimanjaro's main summit Kibo has openings called fumaroles that sometimes emit gas and steam from beneath the earth's surface. Climbers can spot some of them on the part of the mountain known as the Western Breach, a gap formed by ancient lava flows on its western rim.