Humboldt County, California in the context of "Petrolia, California"

The Mattole River is a river on the north coast of California, that flows northerly, then westerly into the Pacific Ocean. The vast majority of its 62 miles (100 km) course is through southern Humboldt County, though a short section of the river flows through northern Mendocino County. Communities, from north to south, closely associated with the Mattole River include: Petrolia, Honeydew, Ettersburg, Thorn Junction, and Whitethorn. The river enters the ocean at the Mattole Estuary about 4 miles (6.4 km) west-southwest of Petrolia and 10 miles (16 km) south of Cape Mendocino.

The Coast Ranges of California span 400 miles (644 km) from Del Norte or Humboldt County, California, south to Santa Barbara County. The other three coastal California mountain ranges are the Transverse Ranges, Peninsular Ranges and the Klamath Mountains.

Physiographically, they are a section of the larger Pacific Border province, which in turn is part of the larger Pacific Mountain System physiographic division. UNESCO has included the "California Coast Ranges Biosphere Reserve" in its Man and the Biosphere Programme of World Network of Biosphere Reserves since 1983.

40°14′40″N 124°07′22″W / 40.24444°N 124.12278°W / 40.24444; -124.12278

Honeydew (formerly Honey Dew) is an unincorporated community in Humboldt County, California. It is located 17 miles (27 km) south of Scotia at an elevation of 322 feet (98 m), on the Lost Coast of the Pacific Ocean, near the King Range mountains. There are a general store, elementary school, post office, and a few houses nearby. Many of the locals live in the hills surrounding the Mattole valley, named for the Mattole River, which runs through the valley. The ZIP code is 95545, and the community is inside area code 707.

Ettersburg (also, Etter) is a locality in Humboldt County, California. It is located 12.5 miles (20 km) west-northwest of Phillipsville, at an elevation of 676 feet (206 m).

40°01′26″N 123°56′35″W / 40.02389°N 123.94306°W / 40.02389; -123.94306

Whitethorn (formerly Thorn) is an unincorporated community in Humboldt County, California, United States. It is located 9.5 miles (15 kilometers) southwest of Garberville, at an elevation of 1,024 feet (312 meters), with a population of 817. Whitethorn shares a ZIP Code, 95589, with Shelter Cove, California. It is located along California's Lost Coast.

Cape Mendocino (Spanish: Cabo Mendocino, meaning "Cape of Mendoza"), which is located approximately 200 miles (320 km) north of San Francisco, is located on the Lost Coast entirely within Humboldt County, California, United States. At 124° 24' 34" W longitude, it is the westernmost point on the coast of California. The South Cape Mendocino State Marine Reserve and Sugarloaf Island are immediately offshore, although closed to public access due to their protected status. Sugarloaf Island is cited as California's westernmost island.

Eureka (/jʊˈriːkə/ yuurr-EE-kə; Wiyot: Jaroujiji; Hupa: dahwilahłding; Karok: Uuth) is a city in and the county seat of Humboldt County, located on the North Coast of California. The city is located on U.S. Route 101 on the shores of Humboldt Bay, 270 miles (435 km) north of San Francisco and 100 miles (161 km) south of the Oregon border. At the 2020 census, the population of the city was 26,512 and the population of the greater Eureka area was 48,119.

Eureka is the largest coastal city between San Francisco and Portland, Oregon, and the westernmost city of more than 25,000 residents in the 48 contiguous states. The proximity to the sea causes the city to have an extremely maritime climate with very small annual temperature differences and seasons mainly being defined by the rainy winters and dry summers, whereas nearby inland areas are much hotter in summer. It is the regional center for government, health care, trade, and the arts on the North Coast north of the San Francisco Bay Area. Greater Eureka, one of California's major commercial fishing ports, is the location of the largest deep-water port between San Francisco and Coos Bay, a stretch of about 500 miles (805 km).

The North Coast of California (also called the Redwood Empire or the Redwood Coast in reference to the dense redwood forests throughout the region) is a region in Northern California that lies on the Pacific coast between San Francisco Bay and the Oregon border. It commonly includes Mendocino, Humboldt, and Del Norte counties and sometimes includes Lake and two counties from the San Francisco Bay Area, Marin and Sonoma.