A small island in San Francisco Bay, once a prison, that lies in the path of the USS Vengeance when it crashes into the city in Star Trek Into Darkness.
Alcatraz is a rocky island in San Francisco Bay, known for the federal prison that operated there in the 20th century. Because Starfleet Headquarters and the Academy are in San Francisco, the island can be glimpsed in many of Star Trek's views of the bay.
Its most dramatic moment comes in Star Trek Into Darkness, set in the alternate reality in 2259. After Spock detonates torpedoes aboard the USS Vengeance, Khan aims the crippled dreadnought at Starfleet Headquarters. The huge ship comes down in the bay, tears across Alcatraz and ploughs on into the city's waterfront, levelling buildings.
The crash kills thousands and leads directly to Spock's pursuit of Khan through the streets of the city, and to the rededication of the Enterprise a year later.