[6] At the time of the Spanish colonization of the Americas the island was the domain of the nomadic indigenous Chono people.

The Spanish built a fort on nearby Calbuco Island in 1603 to provide for the protection of this settlement and others in the Gulf of Ancud and Chiloé Archipelago.

[10] The Battle of Abtao took place on 7 February 1866 in the channel that separates the island from Punta Auco on the Challahue peninsula to the northwest.

As part of the blockade on Valparaiso during the Chincha Islands War the Spanish sent two ironclads to destroy the combined Chilean-Bolivian-Peruvian fleet.

[12] There is a small monument on the island to the battle, where, annually, Chilean Navy personnel commemorate the successful repulsing of the enemy.