Diablo Summit Stomp
Walnut Creek, United States • 18 Oct 2025
Event overview
The Diablo Summit Stomp takes place on October 18, 2025, in Walnut Creek, California. The race offers four distances:
- 30K
- Half Marathon
- 10K
- 5K
All distances start from Castle Rock Park and use trails that enter Mount Diablo State Park. The 30K route reaches the summit of Mount Diablo.
Course and logistics
All courses are on dirt trails and will be marked with colored ribbons, signs, and flour. Depending on weather, courses may include mud and creek crossings. Walkers and hikers are allowed in all distances. Water stations will be stocked with water, sports drink, gels, pretzels, and candy. Runners in the 10K, half marathon, and 30K are advised to carry at least two bottles or a large hydration pack; half marathon runners are asked to be cupless where possible, and water station volunteers can refill containers or provide a cup if needed. GPX files and course maps are available for each distance. The 30K has an overall course time limit of 6.5 hours and on-course cut-offs at specific aid stations; the event also allows a mid-race option at Aid Station #3 for 30K runners to switch to the half marathon under the race’s surrender policy. Age group awards are given to the top three finishers in five-year categories, with smaller categories for younger ages. Visit the organization's website for the most recent information.