Half Moon Bay is a coastal city in San Mateo County, California, United States, approximately 25 miles south of San Francisco. Its population was 11,795 as of the 2020 census. Immediately north of Half Moon Bay is Pillar Point Harbor and the unincorporated community of Princeton-by-the-Sea. Half Moon Bay is known for Mavericks, a big-wave surf location. It is called Half Moon Bay because of its crescent shape.