small cluster of islands in the South Pacific Ocean, situated about 400 miles (650 km) west of and administratively part of Chile. They consist of the 36-square-mile (93-square-km) Isla Más a Tierra (Nearer Land Island, also called Isla Robinson Crusoe); the 33-square-mile Isla Más Afuera (Farther Out Island, also called Isla Alejandro Selkirk), 100 miles to the west; and an islet, Isla Santa Clara, southwest of Isla Más a Tierra. The islands are volcanic peaks rising from the Juan Fernández submarine ridge. Más a Tierra has a summit 3,002 ft (915 m) above sea level, and Más Afuera rises to 5,415 ft. Bahía Cumberland (Cumberland Bay), on the northern side of Más a Tierra, and Bahía Padre, at the western extremity, are the only fair anchorages.

The islands were discovered about 1563 by Juan Fernández (Fernández, Juan), a Spanish navigator, who received a grant and lived there for some years, stocking them with goats and pigs. After his departure, the islands were visited only occasionally. In 1704, however, Alexander Selkirk (Selkirk, Alexander) (q.v.), a Scottish seaman, quarreled with his captain and was put ashore at Bahía Cumberland. He remained there alone until 1709 and his adventures are commonly believed to have inspired Daniel Defoe's Robinson Crusoe. The islands passed into Chilean possession in the early 19th century. Since then, they have been used as penal settlements on many occasions, particularly for political prisoners. Isla Santa Clara is now uninhabited. Más a Tierra and Más Afuera are sparsely populated, most of their inhabitants being concentrated in the village of Robinson Crusoe on Bahía Cumberland. Their principal occupation is fishing for lobsters. Pop. (2002) 598.