Blue Sky Trail Marathon

Blue Sky Marathon & Half (October 17-18, 2026)

The Blue Sky races take place in Horsetooth Mountain Park and the Devil’s Backbone Open Space near Fort Collins, Colorado. The event includes two distances:

• 26.7 miles (3,500′ total gain)
• 13.4 miles (1,800′ total gain)

The course minimum and maximum elevations range from 5,300′ to 6,500′; the marathon average elevation is about 5,700′. Registration is capped at 400 runners for each distance. Time allowances are 9 hours for the marathon and 6 hours for the half.

Course, aid stations and rules

The routes are 100% dirt and about 90% singletrack. Marathon terrain breakdown: 22 miles dirt singletrack, 3 miles rocky singletrack, 2 miles dirt road. Half marathon: 13.0 miles dirt singletrack, 0.5 miles dirt road. The course crosses hogbacks and redstone hardpack with sections of technical rock gardens. Wildlife on course includes deer, Abert squirrel and golden eagle.

Aid stations are fully stocked with sports drink (Fuel2O), Hammer gels, water, soda, salty and sweet bites, and fruit. Gluten-free and vegan alternatives are available for most offerings. Marathon runners may leave a drop bag at the Blue Sky Start/Finish; half runners may leave one at South Bay. Portable toilets are provided at start/finish and at Indian Summer North.

Race rules include mandatory 16 oz minimum personal water capacity, no pacers, crewing only at designated locations, no dogs, and enforcement of marathon intermediate cut-offs. Entries are non-refundable. Visit the organization's website for the most recent information.