San Diego Bay is a natural harbor adjacent to San Diego, California. The bay is bordered by the cities of San Diego, National City, Chula Vista, Imperial Beach and Coronado.

The western border of the bay is protected from the Pacific Ocean by a long, narrow strip of land called the Silver Strand . The northern end of the Silver Strand expands to become North Island, the location of Naval Air Station North Island (the home port of several aircraft carriers including the USS Ronald Reagan) and Coronado. Coronado is the site of the famous Hotel del Coronado. The U.S. Navy has two more facilities on the bay, Naval Station San Diego and Point Loma Naval Base at Balast Point , which is a Nuclear Submarine base. The Coast Guard Air Station San Diego is across the bay from NAS North Island and the Federal Communications Commission maintains a monitoring station on the Silver Strand.

San Diego International Airport is also adjacent to the bay, across Harbor Drive from the Coast Guard Station. General Dynamics' National Steel and Shipbuilding Company (NASSCO), the only shipyard on the west coast capable of building and repairing large ocean-going vessels, is near the San Diego side of the graceful San Diego-Coronado Bay Bridge . The bay has two container ship facilities (one for refridgerated containers) and a cruise ship terminal.

Several museum ships call San Diego Bay home. These include the USS Midway, the largest aircraft carrier museum, and the Star of India, the oldest active ship.

The shallow southern end of the bay is used for evaporation ponds to extract salt from the sea water.

The Port of San Diego manages the harbor and administers the public lands adjacent to the bay, including the airport. It is a special government entity created by the state legislature and has its own tax base and police force.