1. The Hardrock 100 Endurance Run was founded in 1991 by Gordon Hardman, to honor the early miners who met the many challenges of the San Juan Mountains.

2. The length of the race is actually 100.5 miles, and a mere .17 miles of that is on pavement. The rest is rugged mountain road and trail.

3. Connecting four historic mining towns – Silverton, Lake City, Ouray and Telluride – runners crest 12,000’ 13 times, 13,000’ seven times, and summit Handies Peak, 14,048’.

4. The average elevation is 11,016’. Runners will climb and descend 33,992’ – a total of 67,984’ – equivalent to running from sea level to the top of Mt. Everest and back.

5. The average age of a Hardrocker is 45. The youngest runner is 27 years old; the oldest is 75. For 2015, 1,200 applicants from 33 countries and 46 states applied to enter the race. One hundred and 29 men, and 23 women got in.

6. Only about 61 percent of participants finish the race.

7. Kirk Apt of Colorado has raced and finished the Hardrock 21 times.

8. The course alternates direction every year and European endurance legend Kilian Jornet now holds the record for both. In the 2014 clockwise race, he finished in 22:24:33, weeks after setting a record speed ascent of Mt. McKinley. In 2015, one week after winning Alaska’s infamous Mt. Marathon, he set a new counter clockwise record of 23:28:10.

9. New Zealand’s celebrated ultra runner Anna Frost won the women’s race in 28:22:47, placing eighth overall in her first Hardrock.

10. Weather and hypothermia are a constant issue, and a number of runners have had brushes with lightning. In 2014, Canadian ultra runner Adam Campbell’s head lamp exploded after a lightning strike on Handies Peak. In 2015, alpine snowstorms presented difficult conditions and challenging route finding. Some runners reported sinking to their waist in deep snow fields.

11. With a mandatory cutoff at 48 hours, it takes most runners 40 hours to finish. This year, Boulder’s Bogie Dumitrescu finished the race in 47:59:59.

12. In order to officially finish, runners must kiss a 2-ton sandstone boulder that sits in downtown Silverton, Colorado that marks the start and finish of the race.

13. Runners can use pacers after 42 miles to accompany them and help them run efficiently. They can also have support crews. There is a wait list to become one of the 300 volunteers who work day and night, often in adverse conditions and in remote environments, to man one of the 13 aid stations.