Santa Monica Mountains National Recreation Area, National recreation area in Los Angeles and Ventura counties, United States

The Santa Monica Mountains National Recreation Area covers 153,075 acres of the Santa Monica Mountains in the Transverse Ranges, two thirds in northwest Los Angeles County and one third, with a Simi Hills extension, in southeastern Ventura County. A long ridge of light brown and tan rock with vertical striations runs across the mountains, its steep slopes covered in green shrubs and patches of dry grass. The National Park Service administers it with state, county, municipal and university agencies.

The area was established in 1978 as a national recreation area after decades of conservation efforts. Earlier protection initiatives dating back to the early 1900s helped preserve these mountains from development and shaped the modern protected landscape.

The park protects one of the highest densities of archaeological resources of any mountain range in the world. Proposals for a park here carried other names first: Sylvia Morrison urged a Whitestone National Park, named for the limestone cliffs, and later bills in Congress proposed Toyon National Park.

The area offers over 500 kilometers of trails for hiking, cycling, and horseback riding at various difficulty levels. The best time to visit is from fall through spring when temperatures are mild and fire season is less active.

Biologists have been studying mountain lions here for over two decades to understand how they adapt to living so close to urban areas. These studies reveal the ways wildlife survives and moves through landscapes shaped by human presence and development.