Blue Sky Trail Marathon
Fort Collins, United States • 18-19 Oct 2025
Blue Sky Marathon & Half : key facts
The Blue Sky Trail Marathon and Half take place October 18-19, 2025 in Fort Collins, Colorado, based at the Blue Sky Trailhead in Horsetooth Mountain Park. Two distances are offered:
- 26.7 miles (approx. 3,500 ft elevation gain/loss)
- 13.4 miles (approx. 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. Registration is capped at 400 entries for each distance. Official time allowances are 9 hours for the marathon and 6 hours for the half; the marathon also has intermediate cut-off points at specific aid stations.
Course, aid stations and logistics
Both courses are 100% dirt, with about 90% singletrack. Marathon surface breakdown: 22 mi dirt singletrack, 3 mi rocky singletrack, 2 mi dirt road. Half marathon surface: 13.0 mi dirt singletrack, 0.5 mi dirt road. Aid stations provide water, Gnarly Fuel2O drink mix, Hammer gels, soda, salty and sweet foods and fruit; gluten-free and vegan alternatives are available on request. Marathon runners may leave a drop bag at the Blue Sky start/finish; half runners may leave one at South Bay. Toilets are available at start/finish and at Indian Summer North. Crewing and pacing rules vary by course: crewing is restricted to designated locations and is not allowed at some aid stations; pacers are prohibited. Parking for runners is in designated lots; vehicles with registered runners receive a park pass. Visit the organization's website for the most recent information.