12hr ultramarathons in Colorado, United States

Scenic alpine 10K loop with 1,546 feet of vertical gain per lap, technical trails through aspen groves and meadows at Powderhorn Mountain

2km out-and-back laps on the Thumb Open Space trail, with 540 feet of climbing each lap and a sustained focus on vertical gain.

Lap-based ultra in Montezuma County’s high desert with steep climbs, rocky descents, and views of Mesa Verde and Sleeping Ute Mountain.

Scenic, flat one-mile dirt loop with runner-friendly terrain and all-day support in a communal atmosphere

Trail loops in challenging winter conditions supporting air quality nonprofits and environmental education

Private trails at Sylvan Dale Guest Ranch with varied terrain and picturesque views, featuring individual and relay formats with on-site aid station support.

Timed ultra in Mueller State Park with a draw-by-chance loop format and all-dirt double-track and single-track trails.

Flat, fast cross-country loop on dirt, grass, and gravel with minimal elevation gain, Rocky Mountain views, and a course winding past rescued animals

Overnight 12-hour ultramarathon on Highlands Ranch singletrack, with solo or relay options, full moon views, and Rocky Mountain scenery