Golden Gate Headlands Marathon, Half Marathon & 10K
Saturday, Mar. 31, 2018
Sausalito, CA

https://raceroster.com/events/2018/12895/2018-golden-gate-headlands-marathon-half-marathon-10k

Description from event page:

You'll start and finish at the historic parade ground at Ft. Barry in Rodeo Valley. Along this scenic trail run through the Marin Headlands, you'll soak in panoramic vistas of the Golden Gate Bridge, the San Francisco Bay and the lush Pacific shoreline peppered with vibrant wildflowers. The course is a combination of single track hiking trails and fire roads. The event is limited to 400 participants and sells out every year so don't wait too long to register!