Diablo Trails Challenge
Walnut Creek, United States • 4 Apr 2026
Event overview
The Diablo Trails Challenge is a trail running event on Mount Diablo in Walnut Creek, California. It takes place on April 4, 2026 at 1700 Castle Rock Road, Walnut Creek, CA 94598, United States. The event is organized by Brazen Racing and includes multiple trail distances:
- 50K
- Half marathon
- 10K
- 5K
- Remote runner option
The half marathon at this event is part of the Brazen Ultra Half Series. The series features half marathons that run longer than a standard 13.1 miles and include notable ascents and descents on trail terrain. Photos from the race are provided by volunteer photographers and official results are published after the event.
Registration, fees and charity
Registration is tiered by date and distance. Example early prices shown are: 50K $159.17, half marathon $105.80, 10K $86.58, 5K $76.98, and remote runner $50.29. A BBQ lunch plate option is available for purchase. A portion of all entry fees will be donated to Save Mount Diablo to support preservation of open space and trails around Mount Diablo. Volunteer opportunities and fundraising options are available for the event. Visit the organization's website for the most recent information.