Diablo Summit Stomp
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Event overview
The Diablo Summit Stomp takes place on October 18, 2025, at Castle Rock Park / Mount Diablo State Park in Walnut Creek, California. The event offers four trail distances:
- 30K
- Half Marathon
- 10K
- 5K
Walkers and hikers are allowed in all distances. Age group awards are given to the top three finishers in five-year categories, with smaller categories for younger ages.
Course, support and rules
All courses run on dirt trails through Castle Rock and Mount Diablo State Park, with the 30K route reaching the summit. Courses may include mud and creek crossings depending on weather. Routes are marked with colored ribbons, signs, and flour; course maps, elevation charts, and GPX files are provided for navigation.
Water stations supply water, sports drink, gels, pretzels, and candy. Runners in the 10K, half marathon, and 30K are recommended to carry at least two bottles or a large hydration pack. Half marathon runners are encouraged to be "cupless" at water stations; volunteers can refill containers or provide cups if necessary. The 30K has an overall time limit of 6.5 hours. Runners on the 30K may have the option to switch to the half marathon at a specified aid station under event conditions; those who switch are recorded as half marathon finishers but are not eligible for overall or age group awards and are listed in the "surrender" category. Visit the organization's website for the most recent information.