The Big Alta

The Big Alta

The Big Alta is a three day trail running event held March 19, 20 and 21, 2027 in Marin County, California, staged at Marinwood Community Center and Park in San Rafael. The event offers three race distances across a weekend of single loop and point to point courses.

Distances

• 50K single loop course
• 100K new point to point course
• 28K single loop course

Courses ascend many of Marin County's highest points and pass landmarks such as Loma Alta and Big Rock Ridge, with views across the San Francisco Bay Area. Each race day is limited to 300 runners. Registration is handled through UltraSignup and fees are tiered by registration period; example entry fees listed for 2027 include $300 for the 100K, $175 to $195 for the 50K, and $140 to $155 for the 28K.

Included with registration are a fully marked course, chip timing, live on course splits and results, staffed aid stations, professional medical support, shuttle buses, post race food and beverages, custom finisher awards, professional photography and required permitting. The 100K requires participants to carry the course GPX file on a navigation device during the race. A shuttle bus option to the 100K start is available for an additional fee. Friendly leashed dogs are allowed at the staging area but not on course. The organizers acknowledge the traditional lands of the Coast Miwok people. Visit the organization's website for the most recent information.