San Diego 100
Lake Cuyamaca, United States • 1 May 2026
Event overview
The San Diego 100 is a 100 Miler ultramarathon held at Lake Cuyamaca Recreation Area, near Julian, California. The race is a loop course that is roughly 90% single-track mountain trail and covers sections of the Pacific Crest Trail, Noble Canyon, Cuyamaca and Anza Borrego State Parks, and Mount Laguna recreational areas. The course has about 15,400 feet of ascent and the same amount of descent. The event has a 32 hour time limit and is a qualifier for Western States 100.
Course, entry and rules
The start and finish area is at the south parking of Lake Cuyamaca Recreation Area, located on State Highway 79 about 9 miles southwest of Julian. The course is described as technical and typically hot and dry. Aid stations and drop bags are part of the support system on course.
Entry requires a qualifying performance: completion of a 50 mile race in under 13 hours, or completion of a 100K or 100 mile within that race’s time limits, achieved between January 1, 2023 and May 1, 2025. Applicants who lack a qualifier at sign-up must provide one by May 1, 2025. Entrants must also complete six hours of trail maintenance or other volunteer service between June 1, 2024 and May 15, 2025, or donate $100 to support volunteers and Trailfit; this requirement is strictly enforced. A Solo Division recognizes runners who complete the race without crew or pacers and limits spectator contact to the start and finish. Visit the organization's website for the most recent information.