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Online registration is closed. Race day registration will be available. Read the race day details online here.

It doesn't get much better than this coastal ridge trail run. Enjoy the rolling singletrack high up on Mt. Tam with views of the Pacific Ocean below. You will follow a combination of paved roadways and dirt singletrack trails offering striking views of Bolinas Lagoon, the Pacific Ocean and Marin County watershed. From the start at Rock Springs, the course follows Ridgecrest Blvd. along the spine of Bolinas Ridge separating East and West Marin County. 10K runners will take a left at Willow Camp Trail and head back to Rock Springs along the Coastal Trail. The Half Marathon course continues along Ridgecrest Blvd. to Bolinas/Fairfax Road and also returns via the Coastal Trail. The event is limited to 300 participants so don't wait too long to register!

Registration fees

Course Map

Link to Course Map

COURSE CUT-OFF TIME3 HOURS (13:45min/mile pace for half marathoners, 29min/mile for 10Kers). Hikers/Walkers are welcome to participate.

Half Marathon Elevation Profile

10K Elevation Profile

Additional Details

COURSE MARKINGS: The course will be marked with orange ribbon. A course monitor will guide the 10Kers on when to turn. The half marathon turnaround is designated by a sign.

AID STATIONS: The 10K has one aid station at mile 5. The half marathon has aid stations at mile 2.35, 7 and 12. There will also be food/drink available at the finish. We highly recommend that you carry water.

INCENTIVES: T-Shirts for all participants. Rubber chicken to the first place overall male & female in each distance. Personalized award ribbons to the top three finishers, male and female, in each age group for all distances which will be mailed out a few weeks after the race. Two pairs of Merrell shoes raffled off to two lucky runners at the race.

BIB NUMBERS: Bib numbers will be mailed out to participants beginning two weeks before the event. If you do NOT receive a bib prior to race day, you will pick one up on race day morning. If you did not supply a valid mailing address when you registered, or if your mailing address has changed, please e-mail us at

PARKING: is available in the Rock Springs Parking area in Mt. Tamalpais State Park. Parking attendants will guide you on where to go once you enter the park.

DRIVING DIRECTIONS: Google Maps Link to Parking Area.

CANCELLATIONS: Registrations are non-refundable and non-transferable. If you email us by March 6, you may receive a rollover credit (the amount you paid minus a $10 fee) to use toward any future Enviro-Sports race.

HEADPHONES POLICY: Since parts of this race include very narrow trails with steep drop-offs along the course, it is imperative that runners can hear each other in order to pass safely, even if they are running at a slow speed. For safety reasons (and for the enjoyment of your fellow runners) headphones (and any other audio devices) are NOT allowed. 

Event Partners




Event Schedule

  • April 13 7:20 AM PDT - Athlete Check-in

  • April 13 8:10 AM PDT - Pre-race announcements

  • April 13 8:20 AM PDT - Race Start

Contact Information

Event Location

Mt Tamalpais State Park, Mill Valley, CA, United States

Click here to view map