San Francisco Bay, enormous, about landlocked inlet indenting western California, U.S. It is a suffocated stream valley paralleling the coastline and is associated with the Pacific Ocean by a strait called the Golden Gate, which is spread over by the Golden Gate Bridge.
San Francisco Bay is 60 miles (97 km) long and 3 to 12 miles (5 to 19 km) wide and is one of the world’s best regular harbors. Fortune, Yerba Buena, Angel, and Alcatraz islands lie in it, and a few extensions interface its eastern and western shores. Around the sound are San Francisco, Oakland, and a band of coterminous metropolitan subcentres connected by the Bay Area Rapid Transit (BART).