Eureka is the principal city and the county seat of Humboldt County, California, United States.
Eureka is the largest Pacific coastal city between San Francisco and Portland, Oregon. The port city serves as the center for government, health care, trade, and the arts for the far North Coast region of California. Its location adjacent to Humboldt Bay 270 miles (430 km) north of San Francisco (via U.S. Route 101) includes marinas and industrial docking facilities, making it the largest port between San Francisco and Coos Bay, a distance of about 500 miles. As the primary full-service city situated between the most extensive preserves of the world's tallest trees, the Coast Redwoods, and dozens of related parks, Eureka is the site of the headquarters for both the North Coast Redwoods District of the California State Parks System and the Six Rivers National Forest.
The city, a major player in the historic west coast lumber trade, is the site of hundreds of significant Victorian homes, including the Carson Mansion, situated at the head of its Old Town Historic District. Eureka is also site of the Sequoia Park Zoo, California's oldest zoo.