Ultramarathons Near Denver, CO
As of October 6, 2026, Crewable lists 20 upcoming ultramarathons near Denver, CO from October 2026 to September 2027. The next is Rocky's Backyard Ultra on October 10 in Estes Park, CO. Registration is open for 5. 2 advertise prize money.
Sources: UltraSignup, RunSignUp, UTMB, race organizers and race websites
With aid station data
13 aidin 11 days
Blue Sky Trail Marathon & Half Marathon
Fort Collins, CO3,500 ft gain
MarathonHalf Marathon
Open until Oct 17from $110
6 aid
1 aid
1 aid
1 aidRace calendar
October 2026
6 racesBlue Sky Trail Marathon & Half Marathon
Fort Collins, CO3,500 ft gainMarathonHalf MarathonOpen until Oct 17from $110
November 2026
4 racesDecember 2026
2 racesApril 2027
2 racesMay 2027
2 racesJuly 2027
1 raceAugust 2027
1 raceSeptember 2027
2 racesQuick answers
What is the next ultramarathon near Denver, CO?
Rocky's Backyard Ultra, on Saturday, October 10, 2026, in Estes Park, CO. Distances: Backyard Ultra.
What is the closest ultramarathon to Denver?
11th Hour Bear Creek Backyard Ultra in Lakewood, CO, about 11 miles from Denver, on October 31, 2026.
How many ultramarathons near Denver, CO have open registration?
5 of the 20 list registration as open as of October 6, 2026, including Blue Sky Trail Marathon & Half Marathon, Bobcat Trail Races and Indian Creek Trail Runs.
Which ultramarathons near Denver, CO offer prize money?
2 races advertise prize money, including Rocky's Backyard Ultra ($1,000).
What is the busiest month for ultramarathons near Denver, CO?
October 2026, with 6 of the 20. November 2026 follows with 4.
Nearby cities
Nearby states
More ways to browse
Race planning
Plan your Denver race
Aid stations, cutoffs and pacing in one free plan. Crew invites and race-day updates come with a Race Pass.
Plan a race free