The 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 the islands Nueva, Picton, Navarino, Hoste, Londonderry, Stewart Islands and other smaller to the south. Its eastern portion is part of the border between Chile and Argentina, but the western part is completely within Chile. The west end is the Darwin Sound and the east end is Nueva Island.

The Beagle Channel, the Straits of Magellan to the north, and the open ocean Drake Passage to the south are the three navigable passages around South America between the Pacific and the Atlantic oceans. The Beagle Channel and the Straits of Magellan are both very narrow passages which severely limit the size and types of ships that can safely use them, hence, most commercial shipping is done through the Drake Passage.

The Beagle Channel is about 240 kilometres (130 nmi; 150 mi) long and is about 5 kilometres (3 nmi; 3 mi) wide at its narrowest point. To the west the Darwin Sound connects it to the Pacific Ocean. The biggest settlement on the channel is Ushuaia in Argentina followed by Puerto Williams in Chile, two of the southernmost settlements of the world.