San Diego 100
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San Diego 100
The San Diego 100 is a 100 mile loop mountain ultramarathon based at the south parking area of Lake Cuyamaca Recreation Area, nine miles southwest of Julian, CA on state Highway 79. The course is roughly 90 percent single track and traverses sections of the Pacific Crest Trail, Noble Canyon, Cuyamaca and Anza Borrego State Parks, and Mount Laguna recreational areas.
The route includes approximately 15,400 feet of climbing and the same amount of descent. Runners must complete the course within a 32 hour time limit. The course is described as technically demanding and runs in hot, dry conditions.
Registration opens January 1, 2026 and remains open until the field reaches 300 entrants or until April 1, 2026. The race serves as a Western States 100 qualifier. Up to two Scotty Mills Scholarships will be awarded; applicants should prepare a short written submission by December 28.
Entry requires proof of recent performance: completion of a 50 mile race in under 13 hours, or a qualifying 100K or 100 mile performance, within the period January 1, 2024 to April 1, 2026. Entrants must also complete six hours of trail maintenance or volunteer service between June 1, 2025 and May 1, 2026 or donate $100 to support trail work. This requirement is strictly enforced.
The event offers both crewed and Solo divisions. Solo runners rely on drop bags and aid stations, receive a special award, and are restricted from receiving crew or paced support during the race. Visit the organization's website for the most recent information.
