Topanga State Park, California state park in Los Angeles, US.

Topanga State Park is a large protected area in the Santa Monica Mountains with extensive trail networks through oak forests, grasslands, and chaparral ecosystems. The park provides multiple entry points, with Trippet Ranch functioning as the main gateway offering parking and visitor information.

The territory came under Spanish control starting in 1542, shifted to Mexican rule in 1821, and later became part of Rancho San Vicente y Santa Monica. These transitions shaped the region's development over centuries.

The name Topanga comes from a Shoshonean word meaning 'above', referring to the canyon settlement being above the flood waters of Topanga Creek. The Tongva and Chumash peoples lived in the area for thousands of years; groups collectively called the Topanga Culture included both. Visitors can see the name on the brown-and-yellow entrance sign beside the paved road.

Topanga State Park has 36 miles of trails and unimproved roads, with more than 60 trail entrances; the main trailheads are at Trippet Ranch, where the Musch Trail passes Eagle Rock. The Backbone Trail, nearly 70 miles long across the Santa Monica Mountains, can be joined at the Trippet Ranch trailhead. Trails are open to hikers, mountain bikers and horseback riders as posted, and many are wide dirt fire roads.

The park covers 11,000 acres, making it the largest park in the Santa Monica Mountains and, by one measure, the largest park lying within a city's limits. Its boundary runs from Topanga Canyon to Pacific Palisades and Mulholland Drive, with more than 60 trail entrances.