The Big Alta
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The Big Alta : March 20-22, 2026
The Big Alta is a three-day trail running event staged at Marinwood Community Center & Park in San Rafael, California. The event offers three race distances on Freetrail home trails in Marin County. Courses summit many of the highest points in the county and reference landmarks Loma Alta and Big Rock Ridge. The courses are described as scenic with views across the San Francisco Bay Area.
Races, entries and race services
Distances:
- 50K single loop
- 100K point-to-point
- 28K single loop
Registration is handled through UltraSignup. Entry fees vary by registration period: 100K $300/$330, 50K $175/$195, 28K $140/$155. Each race day has a limit of 300 runners; a waitlist is used if a race fills. Transfers are allowed but not into sold-out distances. The registration fee includes chip timing, live on-course splits and results, shuttle buses, staffed aid stations, professional medical support, fully marked courses, post-race food and beverages, custom finisher awards, professional photography and required permitting.
Logistics notes include a shuttle pass available for the 100K for a fee, and the National Parks Service does not allow leaving cars at the 100K start. Leashed dogs are allowed at the staging area but not on course. Organizers may activate an inclement-weather gear requirement that lists items such as a rain jacket, emergency blanket, whistle, ID, nutrition and fluids. Visit the organization's website for the most recent information.
