Juan Fernández Islands, sparsely inhabited island group in the South Pacific Ocean, belonging to Chile. The main islands are Robinson Crusoe (Más a Tierra) and Alejandro Selkirk. The islands are rocky and volcanic in origin. The main occupation is lobster fishing. The island group was probably discovered in 1563 by the Spanish explorer Juan Fernández, for whom the islands are named. A Scottish sailor, Alexander Selkirk, was marooned on the main island between 1704 and 1709, and his experiences are supposed to have inspired the novel Robinson Crusoe, by Daniel Defoe. Area, 180 sq km (70 sq mi).