Trinidad is a seaside city in Humboldt County, located on the Pacific Ocean 8 miles (13 km) north of the Arcata-Eureka Airport and 15 miles (24 km) north of the college town of Arcata. Situated directly above its own North Coast harbor, one of California's smallest incorporated cities by population (367 residents in 2010, up from 311 residents in 2000) is noted for its spectacular coastline with ten public beaches and offshore rocks. These rocks are part of the California Coastal National Monument of which Trinidad is a Gateway City. Fishing operations related to Trinidad Harbor are vital to both local tourism and commercial fishery interests in the region. Trinidad lies at an elevation of 174 feet (53 m).
Yurok Indians settled the bluffs over the bay before 1700 AD at the village of Tsurai. The first European sighting of Trinidad Harbor was by the Portuguese navigator Sebastian Rodriguez Cermeño, who did not make landfall. The next visit was by Bruno de Heceta and Juan Francisco de la Bodega y Quadra of the Spanish Navy. Their two ships anchored in Trinidad Bay on June 9, 1775. On June 11, which was Trinity Sunday, a formal act of possession was conducted. The area was named "la Santisima Trinidad".
Settlers arrived on the James R. Whitting in 1850 and founded the town, renamed Warnersville in honor of R.V. Warner, one of the settlers. The first post office opened in Trinidad in 1851.