Mount Tamalpais State Park, State park in Marin County, United States

Mount Tamalpais State Park is a California state park in Marin County whose main feature is Mount Tamalpais, 2,571 feet (784 m) high. The mountain covers around 25,000 acres, and the park contains mostly redwood and oak forests. Muir Woods National Monument is surrounded by the state park.

The park's history is tied to the Mountain Play, first produced in 1913 and staged every year since. In the 1930s the Cushing Memorial Amphitheatre, a natural-stone open-air theater seating 4,000, was built for these performances. Muir Woods National Monument, surrounded by the park, lies within its bounds.

The Cushing Memorial Theater, known as the Mountain Theater, is a natural-stone open-air amphitheater seating 4,000 people. The Mountain Play has been produced there every year since 1913, staged each spring. In summer the theater hosts free monthly astronomy programs open to the public.

The park maintains roughly 60 miles of hiking trails that connect to a broader 200-mile network across neighboring public lands. Visitors can plan day trips ranging from short walks to longer hikes depending on fitness and time available.

From the summit, visitors can see across a 25-mile radius that includes San Francisco, the Bay Area, and even the Farallon Islands on clear days. This vista from the peak ranks among the most expansive views in Northern California.