Gulf of Corcovado is a large body of water separating the Chiloé Island from the mainland of Chile. Geologically, it is a foreland basin that has been carved out by Quaternary glaciers. Most of the islands of Chiloé Archipelago are located in the gulf. The area is next to the Chiloé National Park, and a large population of blue whales is found there, and it is under threat from salmon farming.