The depth of water under the Golden Gate Bridge is approximately 377 feet (or 115 meters) at its deepest point.
The US Geological Survey, with other research partners, have mapped central San Francisco Bay and its entrance under the Golden Gate Bridge using multibeam echosounders. In 2006, they published a topographical image with indicative depths of the sea floor around Alcatraz and Angel Islands, and the Golden Gate Strait underneath the bridge.
The imaging shows the area below the Golden Gate Bridge as being the deepest part of San Francisco Bay.
