• View of the Golden Gate Bridge, taken from the Marin Headlands, looking towards San Francisco at sunrise.

    Golden Gate

    National Recreation Area California

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  • Tunnel Closure

    The Barry/Baker tunnel on Bunker Road will be closed for maintenance during the weeks of 6/2 and 6/9. The tunnel will be open on the weekends. Please use Conzelman Road instead. More »

  • Muir Beach Overlook closure

    The Muir Beach Overlook will be closed for Accessibility improvements and trail upgrades from June 2 through July 21. Alternate viewpoints are available along Highway 1 between there and Stinson Beach.

Mines and Submarine Defenses

If the big guns failed to stop an enemy vessel far offshore, the next line of defense was three minefields containing over 600 underwater mines outside the Golden Gate. An antisubmarine net located inside the Gate would prevent any submarine that penetrated the minefield from entering the bay.

 
a mineplanting ship
Four mineplanters, like the Spurgin shown here, placed mines outside the Golden Gate. They were supported by a flotilla of smaller craft, including many commandeered crab fishing boats.
PARC, Golden Gate National Recreation Area
 
a mine detonating
A mine containing 3000 pounds of TNT is detonated during a test.
PARC, Golden Gate National Recreation Area
 
photo of a ground mine
Early in the war, buoyant mines were anchored 15 feet below the surface and could be detonated from an onshore control station. "Ground" mines (above), which ships could not foul, later replaced the buoyant mines.
PARC, Golden Gate National Recreation Area
 
photo of Alcatraz prisoner working on antisubmarine buoy
The antisubmarine net that protected the bay was made and serviced at the Tiburon Naval Net Depot and at Alcatraz prison (above). Navy ships would open and close the net for friendly vessels. Here, an Alcatraz prisoner is working on an antisubmarine buoy.
PARC, Golden Gate National Recreation Area

Did You Know?

Fort Baker hospital building

During the early 20th century, the army relied on standardized architectural plans to construct different types of buildings. That is why Fort Baker Building 533 and the Fort Mason GGNRA headquarters’ building look so similar: they were both constructed in 1902 as hospitals.