Mongolia Sunrise to Sunset, Mongolia

Who: 100 runners

When: August 5, 2015

Why it's unique: The full or ultra version of this single track lakeside marathon takes your breath away for a number of reasons – the dark start though the windblown wooded lowland, the 2,400-feet ascent to Chichee pass and, of course, the sweeping views of Hovsgol National Park and its alpine lake, one of the largest single bodies of drinkable fresh water in the world. []