Douglas Strait is a strait 2 nautical miles (4 km) wide between Thule Island and Cook Island, in the South Sandwich Islands. The existence of this strait was first noted by a Russian expedition under Fabian Gottlieb von Bellingshausen in 1820. It was charted in 1930 by Discovery Investigations personnel on the Discovery II and named for Vice-Admiral Sir Percy Douglas, a member of the Discovery Committee.