Course Map: Diablo Trails Challenge Half Marathon

Runners follow an out-and-back figure-eight-shaped loop course for the Diablo Trails Challenge Half Marathon, which starts and finishes at Castle Rock Park just outside Walnut Creek and just east of San Francisco. From there, the course heads out onto the trails that straddle the border between Diablo Foothills Regional Park and Mount Diablo State Park, along a combination of trails and park roads, before bringing runners back to the starting area for the race finish. (MORE: Diablo Trails Challenge Half Marathon event details)

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Note: The course map above provides the approximate route for the race. Though every effort has been made to ensure its accuracy, changes are sometimes made to race routes due to weather conditions, road closures or other circumstances that can require a course to be changed. If you see an error above, email us here.