Diablo Trails Challenge
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Event details
Diablo Trails Challenge takes place on April 4, 2026, at 1700 Castle Rock Road, Walnut Creek, California. The event offers trail race options in multiple distances:
- 50K
- Half Marathon
- 10K
- 5K
The half marathon is included in the Brazen Ultra Half Series. The race is organized by Brazen Racing and is held on and around Mount Diablo.
Registration, fees and beneficiary
Registration fees vary by distance and increase in phases as the event date approaches. Early listed prices include $159.17 for the 50K, $105.80 for the half marathon, $86.58 for the 10K, $76.98 for the 5K, and a $50.29 remote runner option. A separate BBQ lunch plate ticket is available for $23.60.
A portion of all entry fees will go to Save Mount Diablo. The organization has worked to increase protected open space from 6,788 acres to over 100,000 acres on and around Mount Diablo. Visit the organization's website for the most recent information.