When was Alcatraz Island first discovered?

Alcatraz Island was first discovered by Europeans in 1775 when Spanish explorer Juan Manuel de Ayala charted San Francisco Bay and named the island "La Isla de los Alcatraces," meaning "Island of the Pelicans." However, the island was already known to Native Americans long before European contact. It became notable later when it was used as a military fortification and eventually as a federal prison.