Half Moon Bay State Beach, State beach in San Mateo County, US.

Half Moon Bay State Beach is a 4-mile (6 km) protected stretch of Pacific coastline in San Mateo County, made up of four beaches from north to south: Roosevelt, Dunes, Venice and Francis. The 181-acre park was established in 1956. Its broad, flat tan sand slopes gently to the water, marked by tire tracks and footprints, with a line of white foam where the waves wash in.

The Ohlone lived along the San Mateo County coast for thousands of years in small, scattered villages. The Spanish Portolà expedition camped near the shore on October 28–29, 1769, and Juan Crespi recorded Pillar Point in his diary. After Mission Dolores was founded in 1776 the coast served for grazing mission livestock; secularization in 1834 produced Rancho Miramontes (1841) south of Pilarcitos Creek and Rancho Corral de Tierra (1839) to the north. The park was established in 1956.

The name Half Moon Bay comes from the bay's crescent shape; the town was called Spanishtown before Anglo settlers arrived in the 1850s, and the post office spelling changed to Half Moon Bay in 1905. Francis Beach hosts a 52-site campground, and the beaches are used for sunbathing, fishing, picnicking and surfing.

The park runs four miles from Roosevelt Beach in the north to Francis Beach in the south, with Dunes and Venice between. Francis Beach holds the 52-site campground; tent sites and trailer or RV sites are separated, and there are no RV hookups, though a dump station is available. A county trail at the north end, below Pillar Point, carries hikers and bikers down to the ocean.

Half Moon Bay State Beach is known for its rare western snowy plover colony, which nests on the sand. Offshore, some of California's tallest surf rises at Mavericks after big storms, and the annual Mavericks Surf Contest is held there. The beach is also a productive fishing spot, with English sole, rockfish and lingcod among the most abundant species.