San Diego 100

The San Diego 100 is a challenging 100-mile ultramarathon held in the mountainous east county of San Diego, California, starting and finishing at Lake Cuyamaca Recreation Area. The course is a 90% single-track loop traversing four recreational areas, including sections of the Pacific Crest Trail, Noble Canyon, Cuyamaca and Anza Borrego State Parks, and Mt Laguna. Runners face approximately 15,400 feet of elevation gain and loss in hot, dry conditions, with a 32-hour cutoff.

The race features strong volunteer support, a Solo Division for uncrewed runners, and serves as a Western States 100 qualifier. Participants must meet qualifying standards and complete volunteer service or donate to trail maintenance. Visit the organization's website for the most recent information.