Big Basin Redwoods State Park is a state park in the U.S. state of California, located in Santa Cruz County, about 36 km northwest of Santa Cruz. The park contains almost all of the Waddell Creek watershed, which was formed by the seismic uplift of its rim, and the erosion of its center by the many streams in its bowl-shaped depression. Big Basin is California's oldest State Park, established in 1902, earning its designation as a California Historical Landmark.