This island was inhabited by the Knights Templar in the 12th and 13th centuries. After their expulsion and dissolution, it passed to the Crown of Aragón, who donated it to the Bishopric of Tui in 1370 in appreciation for their loyalty. The following years were a series of periods when it was occupied by religious orders and other periods of abandonment, raids and attacks by British pirates, led by Sir Francis Drake. The Battle of Rande was fought in 1702, in which Anglo-Dutch troops won against the Franco-Spanish fleet. They raided the coast and set fire to the monastery of San Simón, which ended up destroyed and completely abandoned after another English attack in 1719.
After being left abandoned for almost a century, an isolation hospital was built on the island due to the Cholera epidemic, and all vessels coming from Europe were required to make a stop there. The hospital was operational from 1841 to 1927, when it was converted into a prison because of the Civil War. In 1948 it became the summer residence of Franco’s guards, but in 1950 there was a shipwreck in which 43 of them lost their lives. This event resulted in the closure of the island, which only opened again between 1955 and 1963 to become a home for orphaned children.
Today the island is available for visits by appointment. It was heavily restored and is now a centre for the Recovery of Historical Memory, housing several buildings like an archive and a library.