San Diego 100

Event overview

The San Diego 100 is a 100 mile loop ultramarathon held at Lake Cuyamaca Recreation Area near Julian, California. The 2026 race date is May 1-2, 2026. The event is open to both crewed and solo entrants and serves as a qualifier for the Western States 100. Registration opens January 1, 2026 and will remain open until the field reaches 300 entrants or until April 15, 2026; an ordered waitlist will be kept if the race fills.

Course, divisions and entry requirements

The course is approximately 90% single-track trail and traverses sections of the Pacific Crest Trail, Noble Canyon, Cuyamaca and Anza Borrego State Parks, and Mount Laguna recreational areas. The route includes about 15,400 feet of climbing and the same amount of descent, and has a 32 hour time limit. The Solo division requires runners to complete the race without crew or pacers; solo runners may be met by spectators only at the start and finish and must rely on drop bags and aid stations for support. Solo entrants receive a $10 discount and switching out of Solo after registration requires a $10 fee.

Applicants must have completed a 50-mile race in under 13 hours between January 1, 2024 and April 1, 2026, or an equivalent 100K/100-mile performance within that same timeframe. Entrants must also complete six hours of trail maintenance or volunteer service in the specified window or donate $100 in lieu of service. Up to two free entries will be awarded to applicants who submit a brief community service statement by December 28. Visit the organization's website for the most recent information.