San Francisco Bay is located in the state of California. The Estuary encompasses an area of approximately 1,600 square miles. The Bay was formed from tectonic activity. It is the West Coast's largest estuary and its waters drain over 40 percent of the state of California. San Francisco Bay has over 275 miles of shoreline. The Bay transfers the waters of the Sacramento and San Joaquin Rivers into the Pacific Ocean. The central portion of the San Francisco Bay has an average depth of 43 feet. The northern and southern area has an average depth of 15 to 17 feet. The Bay's deepest point is 360 feet and is located under the Golden Gate Bridge. The salinity of the Bay ranges from 0.1 parts per thousand near the Delta to about 30 parts per thousand near the Golden Gate area of the Bay.
The Bay supports a complex ecosystem; there are communities of crabs, clams, fish, birds and other organisms. The Estuary also provides many resources for the people that live within the San Francisco Bay area. Californians also use the Bay for recreational activities such as boating, fishing, swimming, and bird watching. The Bay contains six major ports for the shipping industry. Diminishing fisheries, pollution, and urban demand are important environmental concerns for San Francisco Bay. Restoration and maintenance of water quality and management of the Bay are imperative for people living within the Bay area.