Alcatraz Island Light, Lighthouse on Alcatraz Island, San Francisco Bay, US

Alcatraz Island Light is a white concrete tower with an octagonal, pyramidal shaft divided into vertical panels by recessed lines, rising from a masonry foundation at the southern end of the island near the prison entrance. A small rectangular window sits midway up the shaft; at the top, a gallery with a dark metal railing surrounds a white multi-sided lantern housing with a domed roof. It stands 84 feet tall, 214 feet above sea level.

The first lighthouse was completed in 1854, lit on June 1 by keeper Michael Cassin with a third-order Fresnel lens, and was the first on the U.S. West Coast. Damaged in the April 18, 1906 earthquake, it was replaced by the present 84-foot concrete tower built to the south in 1909, since the new cell house would block its light. The old tower served as a storehouse until demolished in 1912–13.

The lighthouse represents a crucial period of maritime development during the California Gold Rush, when safe navigation became essential for increasing vessel traffic.

The tower is accessible via scheduled ferry service from San Francisco to Alcatraz Island National Park, where the National Park Service manages the automated operation. Visitors should expect windy conditions on the island and remember that the light remains active for maritime use.

The light remained operational during the prison years and guards assisted in operating the fog signals based on weather conditions. This daily collaboration between lighthouse keepers and prison staff was an unusual feature of the island operation.