Arcata is a city adjacent to the Arcata Bay (northern) portion of Humboldt Bay in Humboldt County. >>>> Humboldt Bay is a natural bayand a multi-basin, bar-built coastal lagoon located on the rugged North Coast of California, United States entirely within Humboldt County. The regional center and county seat of Eureka and the college town of Arcata adjoin the bay, which is the second largest enclosed bay in California. In addition to being a seasonal or permanent home to more than 200 bird species and 100 species of fish, the second largest estuary in California is the site of the largest commercial oyster production operation in the state. Harbor facilities include large industrial docks at Samoa and Fields Landing and several marinas located in Eureka which are capable of serving hundreds of small to mid-size boats and pleasure craft.