The largest estuary on the Pacific Coast is San Francisco Bay.

San Francisco Bay, located along the coast of California, is the largest estuary on the Pacific Coast of North America. This estuary connects the Pacific Ocean to the Sacramento and San Joaquin rivers, forming a critical habitat for diverse marine life, migratory birds, and plant species. The bay is vital to California's economy, supporting fishing, tourism, and trade through the nearby Port of Oakland. In addition to its ecological significance, San Francisco Bay faces ongoing conservation challenges, such as pollution, habitat loss, and rising sea levels. Efforts to protect and restore this unique estuarine environment are essential for maintaining its ecological health and economic value.