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

Contact the Park

Mailing Address:

Golden Gate National Recreation Area
Building 201, Fort Mason

San Francisco, CA 94123-0022

Phone:

(415) 561-4700
Pacific West Region Information Center (415) 561-4700 Special Event & Commercial Film Permits (415) 561-4300

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