San Francisco Bay is a shallow, productive estuary through which water draining from approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean. Technically, both rivers flow into Suisun Bay, which flows through the Carquinez Strait to meet with the Napa River at the entrance to San Pablo Bay, which connects at its south end to San Francisco Bay, although the entire group of interconnected bays are often referred to as "San Francisco Bay."

San Francisco Bay is known for several incidents involving bizarre, grotesque monsters. The subversive terrorist organization known as A.I.M. maintained an undersea base in the bay which contained a variety of scientific experiments involving mutated sea life. Several years ago, the Champions of Los Angeles raided the base, accidentally unleashing many of A.I.M.'s mutated experiments. The monsters ran amok and Champions member Darkstar was gravely injured.^[1]

That same year, San Francisco Bay became one of many locales terrorized by the mutated dinosaur known as Godzilla. The Champions arrived once again to safeguard the Bay area, this time working alongside the forces of S.H.I.E.L.D. and the impromptu S.H.I.E.L.D. detachment appropriately named the Godzilla Squad. The battle caused widespread damage, including the destruction of one of America's most familiar landmarks, the Golden Gate Bridge (it was later reconstructed).^[2]

In more recent years, San Francisco Bay has seen an increase of heroic activity, due largely to the city's newest super-hero team, the X-Men. Members of the team crossed the bay to get from the mainland to their new headquarters the Graymalkin Industries.^[3]

At this time, San Francisco Bay was also the scene of heavy action when the Skrull Armada sent a landing crew to the city as part of its Secret Invasion of Earth.^[4]