It is one of the largest islands in Chile, with an area of 5,110 square kilometres (1,970 sq mi).

The narrow Fitzroy Channel connects both bodies of water and separates the island from mainland Patagonia.

Riesco Island hosts Chile's largest known coal reserves, with mining activities dating back to 1880.

[1] It is thought to contain more than 300 million tonnes of low-quality coal in three deposits located in the colonized portion of the island: Río Eduardo, Elena and Estancia Invierno.

In the southwestern portion of the island, Córdova Peninsula marks the eastern limit of the Strait of Magellan and is home to several mountain glaciers.