Alcatraz Island is located in the middle of San Francisco Bay in California. It was formerly used as a military stockade and later as a maximum security prison. Today, the island is a historic site supervised by the National Park Service as part of the Golden Gate National Recreation Area and is open to tours. Visitors can reach the island by ferry ride from Fisherman's Wharf in San Francisco. It is listed as a National Historic Landmark. Its name comes from the Spanish word for gannet.