San Diego 100
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San Diego 100
The San Diego 100 is a 100-mile mountain ultramarathon held at Lake Cuyamaca Recreation Area with a loop course that is approximately 90% single-track. The route traverses sections of the Pacific Crest Trail, Noble Canyon, Cuyamaca and Anza Borrego State Parks, and Mt Laguna recreational areas. The course is technical and takes place in typically hot, dry conditions. Total climbing is approximately 15,600 feet with an equal amount of descent. The event has a 32 hour completion limit and serves as a qualifier for Western States 100.
Location and distances
- 100 Miler Crewed
- 100 Miler Solo
Entry and qualification requirements include completion of a 50 mile race in under 13 hours between January 1, 2025 and April 1, 2027, or completion of a 100K or 100 mile within the time limits in that same timeframe. Applicants may register without a qualifier but must produce one by April 1, 2027. Registration opens January 1, 2027 and will remain open until 200 entrants register or until April 15, 2027; an ordered waitlist will be kept if the race fills.
Participation requirements include six hours of trail maintenance or volunteer service between May 1, 2026 and April 15, 2027, or a $100 donation to support volunteers and Trailfit. Runners over 60 may start one hour early but should be prepared to self-support until the Cuyamaca Peak aid station because aid stations open at their usual times.
The Solo division restricts support to drop bags and aid stations with spectators, pacers, and crew allowed only at the start and finish. Solo finishers receive special awards including a unique belt buckle. The event offers up to two Scotty Mills scholarship entries and a 10 percent discount for active military and first responders. Visit the organization's website for the most recent information.
