The Hardrock Hundred Mile Endurance Run is an ultramarathon of 102.5 miles in length, plus 33,197 feet of climb and 33,197 feet of descent for a total elevation change of 66,394 feet, at an average elevation of over 11,000 feet. The run is held on a loop course on 4WD roads, dirt trails, and cross country in Southern Colorado's San Juan Range, USA. In 2025, the run will be in the counter-clockwise direction.

The run starts and ends in Silverton, Colorado and travels through the towns of Telluride, Ouray, and the ghost town of Sherman, crossing thirteen major passes in the 12,000' to 13,000' range. Entrants must travel above 12,000 feet (3,700 m) of elevation a total of 13 times, with the highest point on the course being the 14,048' summit of Handies Peak. The run has been held in early July of each year beginning in 1992, except for 1995 (too much snow), 2002 (nearby forest fires), 2019 (too much snow), and 2020 (COVID-19 pandemic). Each year's run is run in the opposite direction of the previous year's event (2024 was run in the clockwise direction, 2025 will be counter-clockwise). In order to complete the event, instead of crossing a finish line, runners are required to "kiss the Hardrock", a picture of a ram's head painted on a large block of stone mining debris.

Information at https://hardrock100.com