Some guys like to run around the block, some like to run a couple of miles, some like to run marathons, and then there are some who like to run across entire mountain ranges, at altitude. For the later type of runner, we’ve got a challenge for you – the Hardrock Hundred Mile Endurance Run.

This ultramarathon is just over 100 miles long (hence the name), and it includes some intense climbing and descending (33,992 feet of climbing and 33,992 feet of descending, to be exact). And runners have just 48 hours to complete it, so even if you think you could finish the course at your own comfortable pace, if you aren’t fast enough, you’re out.

The Hardrock is a loop course run on 4-wheel drive roads and singletrack trails (plus some cross-country sections), which begins and ends in Silverton, Colorado. The course takes runners across 13 mountain passes at altitudes between 12 and 13,000 feet above sea level, with a high point of 14,048 feet (at the summit of Handies Peak), and goes through classic Colorado mountain towns such as Ouray and Telluride.

Those runners hardy enough to complete the race don’t pass through a finish line, but are instead required to kiss a picture of a ram’s head at the end (an experience known as ‘kissing the Hardrock’).

The current fastest runs were made by Kyle Skaggs in 2008 (23:23), and Diana Finkel in 2009 (27:18), and the average time it takes to finish this ultramarathon is a little over 41 hours.

If you think you’re up for this epic challenge, the 19th running of the Hardrock Hundred Endurance Run begins on July 13th in Silverton Colorado.