Blue Sky Trail Marathon
Fort Collins, United States • 18-19 Oct 2025
Event overview
The Blue Sky Marathon & Half takes place October 18-19, 2025 on trails between Horsetooth Mountain Park and Devil’s Backbone Open Space in Fort Collins, Colorado. Distances offered:
- 26.7 miles (3,500 ft elevation gain/loss)
- 13.4 miles (1,800 ft elevation gain/loss)
Course elevations range from 5,300 ft to 6,500 ft, with an average marathon elevation near 5,700 ft. The field is capped at 400 entrants for each distance. Time allowances are 9 hours for the marathon and 6 hours for the half; the marathon includes intermediate cut-offs at some aid stations.
Course, aid and rules
The route is 100% dirt and approximately 90% singletrack. Terrain includes smooth dirt trail, technical rock gardens, redstone hardpack, small sections of dirt road and gravel. The marathon route breakdown lists about 22 miles dirt singletrack, 3 miles rocky singletrack and 2 miles dirt road; the half includes about 13.0 miles dirt singletrack and 0.5 miles dirt road. Wildlife noted on course includes deer, Abert squirrel and golden eagle.
Aid stations provide Gnarly Nutrition Fuel2O, Hammer gels, water, soda, fruit and salty and sweet bites; gluten-free and vegan alternatives are available for nearly all standard offerings. Marathon runners may leave a drop bag at the Blue Sky Start/Finish; half marathoners may leave a drop bag at South Bay. Rules include a minimum 16 oz personal water container (no cups at aid stations), no pacers, restricted crewing locations, no dogs, and no mechanical aids without prior approval. Gender specific shirts, finisher awards and a finish-line meal are provided. Visit the organization's website for the most recent information.