Cortes Island is part of the archipelago known as the Discovery Islands in British Columbia, Canada, which lie beyond the northern end of the Gulf of Georgia, between Vancouver Island and the British Columbia Mainland. It is also considered to be part of the Northern Gulf Islands. Cortes lies on the far side of Quadra Island from the city of Campbell River, separated from Quadra Island by Sutil Channel. To the northeast of Cortes Island, across Lewis Channel, is West Redonda Island. Desolation Sound lies to the east of Cortes Island and, beyond that, the upper end of the Malaspina Peninsula. The island is located roughly halfway between Powell River and Campbell River.