Diablo Trails Challenge
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Diablo Trails Challenge : overview
The Diablo Trails Challenge is a trail running event on Mount Diablo held on April 4, 2026, at 1700 Castle Rock Road, Walnut Creek, CA, United States. The event offers multiple race distances on mountain trails.
Distances
- 50K
- Half marathon
- 10K
- 5K
There is also a remote runner option and a separate BBQ lunch ticket.
Additional details
The event is organized by Brazen Racing and is associated with the Brazen Ultra Half Series; the half marathon is described as an "ultra-half" with courses that often exceed 13.1 miles and include significant ascents and descents. A portion of entry fees will be donated to Save Mount Diablo to support preservation and trail efforts on and around the mountain.
Registration fees are tiered and increase as the event approaches. Official race results and free photos from volunteer photographers are made available after the event. Volunteer roles are listed for those who wish to support the race. Visit the organization's website for the most recent information.