洪堡湾（Humboldt Bay）是美国加利福尼亚州北海岸的一个天然海湾和潟湖。 它整个都位于同名的洪堡县内，是美国西海岸旧金山湾到普吉特湾之间最大的受保护水体， 也形成了旧金山和库斯湾之间最大的港口。 这个海湾附近最大的城市是尤里卡，加上周边的聚居地，整个湾区人口将近八万，即80%的洪堡县人口。 除去人类的聚居地外，这里还生活着100多种植物、300多种无脊椎动物、100多种鱼类和200多种鸟类。

作为加利福尼亚州第二大河口，洪堡湾是西海岸最大的牡蛎养殖基地，超过半数的加利福尼亚州牡蛎都是养殖在这里的。 洪堡湾港（偶尔也称尤里卡港）是一个深水港，有许多个码头用来装卸货物，此外湾区内还有无数个供小型船只及游艇使用的小码头。

Humboldt Bay is an American natural bay and a multi-basin, bar-built coastal lagoon located on the rugged North Coast of California, entirely within Humboldt County. It is the largest protected body of water on the West Coast between San Francisco Bay and Puget Sound, the second largest enclosed bay in California, and the largest port between San Francisco and Coos Bay, Oregon. The largest city adjoining the bay is Eureka, the regional center and county seat of Humboldt County, followed by the college town of Arcata. These primary cities together with adjoining unincorporated communities and several small towns comprise a Humboldt Bay Area total population of nearly 80,000 people, which accounts for nearly 60% of the population of Humboldt County. In addition to being home to more than 100 plant species, 300 invertebrate species, 100 fish species, and 200 bird species, the bay and its complex system of marshes and grasses support hundreds of thousands of migrating and local shore birds. Commercially, this second largest estuary in California houses the largest oyster production operations on the West Coast, producing more than half of all oysters farmed in California.