Valdes Island is located in the Southern Gulf Islands, across Porlier Pass from Galiano Island, between Vancouver Island and the British Columbia mainland. The island covers an area of 9 square miles (23 square kilometres), and is 1 mile (1.6 km) wide and 10 miles (16 km) in length.

In 1908-09 Royal Roads, 2000 Sooke Road, Victoria, BC was built with Koksilah, Saturna Island and Valdes Island sandstones.