WATCH: The Tor Des Géants is One of the World's Toughest (and Longest) Trail Ultras

The Tor Des Géants (TDG) is arguably one of the toughest trail ultras on the planet, and certainly one of the longest. It traverses 205 miles through the Italian alps, starting and ending in the town of Courmayeur. Along the way lies 78,700 feet of climbing (nearly three times that of Everest) over mountain passes and exposed alpine terrain.

It is a non-stop race, meaning that participants don’t pause and sleep at designated points each night.

The 2017 edition kicks off on Monday, September 10. Among the 860 runners toeing the start line will be 10 Americans, including Hardrock third-place finisher Joe Grant, 34, of Boulder, Colorado and Kevin Hadfield, 31, of Basalt, Colorado, who placed second at the Coldwater Rumble 100 in Arizona earlier this year.