The Big Alta
Always double-check with the organizer's website! This page may contain affiliate links.
The Big Alta
The Big Alta is a three day trail race weekend held March 19–21, 2027 in Marin County, staged at Marinwood Community Center & Park with race access to nearby Marin trails and Fort Baker. Registration is handled through UltraSignup and opens September 14.
The event offers three distance options:
- 28K single loop on Sunday
- 50K single loop
- 100K new point to point course
Courses summit multiple high points in Marin County and pass landmarks including Loma Alta and Big Rock Ridge, with long vistas across the San Francisco Bay Area. The 100K is a point to point route and requires each participant to carry the current 100K .gpx file on a navigation device during the race.
Race services listed by the organizers include fully marked courses, chip timing with live splits, staffed aid stations, shuttle buses and drop bag service, professional medical support, radio communications, on course photography, post race food and custom finisher awards. Capacity limits are 350 entries each for the 50K and 28K and 400 for the 100K. Fee windows vary by registration period; listed ranges include 100K $335–$370, 50K $180–$205 and 28K $140–$160.
Parking for participants is curbside along Miller Creek Road; the Marinwood Park lot is reserved for the public, officials and volunteers. Friendly leashed dogs are allowed at the staging area but not on course. The event includes an inclement weather policy and may require additional mandatory gear if conditions warrant. Visit the organization's website for the most recent information.
