Beagle Channel is a strait separating islands of the Tierra del Fuego archipelago, in extreme southern South America. It separates Isla Grande de Tierra del Fuego from several smaller islands to the south. Its eastern portion is part of the border between Chile and Argentina, but the western part is completely within Chile.
Beagle Channel is about 150 miles long and is about three miles wide at its narrowest point. To the west the Darwin Sound connects it to the Pacific Ocean. Although it is navigable by large ships, there are safer waters to the south (Drake Passage) and to the north (Strait of Magellan).