Robert Sibley Volcanic Regional Preserve is located in the Oakland Hills of the East Bay region of the San Francisco Bay Area, California. The park is part of the East Bay Regional Parks District (EBRPD), covers 928 acres (3.76 km2), and lies east of Oakland, partly in Alameda County and partly in Contra Costa County. It can be entered from Oakland via Skyline Boulevard, or from Contra Costa County via Old Tunnel Road.