Big Basin is California's oldest State Park, established in 1902, earning its designation as a California Historical Landmark. Its original 3,800 acres (15 km2) have been increased over the years to over 18,000 acres (73 km2). It is part of the Northern California coastal forests ecoregion and is home to the largest continuous stand of ancient coast redwoods south of San Francisco. It contains 10,800 acres (44 km2) of old-growth forest as well as recovering redwood forest, with mixed conifer, oaks, chaparral and riparian habitats. Elevations in the park vary from sea level to over 600 m (2,000 ft). The climate ranges from foggy and damp near the ocean to sunny, warm ridge tops.