Watch: The Grueling Beauty Of The ‘Toughest Mountain Race’

While it’s hard to specify exactly THE toughest ultramarathon, the UTMB has a strong case.

The UTMB is a beast. Runners cover the distance of four marathons and ascend and descend the height of Mount Everest while circumnavigating Mont Blanc through three countries. Over 103 miles through the Alps, runners don’t sleep, just keep running for over 20 hours. For some, it is beyond imagination.

Meet the race in this video by UTMB title sponsor Columbia Sportswear and Teton Gravity Research.