The Archipelago was home to the marooned sailor Alexander Selkirk from 1704 to 1709, and is thought to have inspired English novelist Daniel Defoe's fictional Robinson Crusoe in his 1719 novel about the character (although the novel is explicitly set in the Caribbean, not in the Juan Fernández Islands).

It is densely wooded and very mountainous and is marked by ridges and numerous deep ravines lead to a steep, rugged coast on the east side of the island off which are tremendous depths.

The south, west and north sides of the island have sandy strips of beach which extend 161 m (528 ft) offshore in places.

The highest peak, Cerro de Los Inocentes, rises to 1,268 m (4,160 ft) in the southwest part of Alejandro Selkirk Island, where there is also a prominent rock with a hole through it.

[4] Alejandro Selkirk Island is the emergent summit of a submarine shield volcano that formed during the Pleistocene epoch.

Alejandro Selkirk has a subtropical climate,[6] moderated by the cold Humboldt Current and the southeast trade winds.

[8] The Masafuera rayadito is endemic to Alejandro Selkirk and one of the rarest South American birds with only 140 individuals left.

The island has been recognised as an Important Bird Area (IBA) by BirdLife International because it supports populations of Stejneger's and Juan Fernandez petrels, as well as the Masafuera rayaditos.