Pescadero Creek is a major stream in Santa Cruz and San Mateo counties in California. At , it is the longest stream in San Mateo County and flows all year from springs in the Santa Cruz Mountains. Its source is at above sea level on the western edge of Castle Rock State Park, with additional headwaters in Portola Redwoods State Park, and its course traverses Pescadero Creek County Park and San Mateo County Memorial Park before entering Pescadero Marsh Natural Preserve at Pescadero State Beach and thence to the Pacific Ocean south of Half Moon Bay.