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 Atlantic Oceans. However, most commercial shipping uses the open-ocean Drake Passage.
The Beagle Channel is about 240 kilometres long and is about 5 kilometres wide at its narrowest point. It extends from Nueva Island in the east to Darwin Sound and Cook Bay of the Pacific Ocean in the west. Some 50 kilometres from its western end it divides into two branches, north and south of Gordon Island. The southwest branch between Hoste Island and Gordon Island enters Cook Bay. The northwest branch between Gordon Island and Isla Grande enters Darwin Sound connecting to the Pacific Ocean by the O'Brien Channel and the Ballenero Channel. The biggest settlement on the channel is Ushuaia in Argentina followed by Puerto Williams in Chile. These are two of the southernmost settlements of the world.
Although it is navigable by large ships, there are safer waters to the south (Drake Passage) and to the north (Strait of Magellan). Under the Treaty of Peace and Friendship of 1984 between Chile and Argentina, ships of other nations navigate with a Chilean pilot between the Strait of Magellan and Ushuaia through the Magdalena Channel and the Cockburn Channel to the Pacific Ocean, then by the Ballenero Channel, the O'Brien Channel and the northwest branch of the Beagle Channel.
The Beagle Channel develops between several islands; to the north lies Argentine-Chilean Isla Grande de Tierra del Fuego, to the south Hoste, Navarino, and Picton and Nueva, which were claimed by Argentina until 1984. The latter two lie at the bi-national eastern entrance to the channel while the western entrance is wholly inside Chile. The western entrance of Beagle Channel is divided by Gordon Island into two channels. Some minor islands exist inside the channel among them Snipe Islet and Gable Island. Except for eastern Isla Grande de Tierra del Fuego and Gable Island all islands mentioned here belong to Chile.
The Yaghan peoples settled the islands along the Murray Channel approximately 10,000 years before present. There are notable archaeological sites indicating such early Yaghan settlement at locations such as Bahia Wulaia on Isla Navarino, site of the Bahia Wulaia Dome Middens.
The channel was named after the ship HMS Beagle during its first hydrographic survey of the coasts of the southern part of South America which lasted from 1826 to 1830. During that expedition, under the overall command of Commander Phillip Parker King, the Beagle's captain Pringle Stokes committed suicide and was replaced by captain Robert FitzRoy. The ship continued the survey in the second voyage of the Beagle under the command of captain FitzRoy, who took Charles Darwin along as a self-funding supernumerary, giving him opportunities as an amateur naturalist. Darwin had his first sight of glaciers when they reached the channel on 29 January 1833, and wrote in his field notebook "It is scarcely possible to imagine anything more beautiful than the beryl-like blue of these glaciers, and especially as contrasted with the dead white of the upper expanse of snow."
Several small islands (Picton, Lennox and Nueva) up to the Cape Horn were the subject of the long-running Beagle conflict between Chile and Argentina; by the terms of a Treaty of Peace and Friendship of 1984 between Chile and Argentina they are now part of Chile. From the 1950s to 1970s several incidents involving the Chilean and Argentine Navy occurred in the waters of the Beagle Channel, for example the 1958 Snipe incident, the 1967 Cruz del Sur incident and the shelling of Quidora the same year. See List of incidents during the Beagle conflict.
Beagle Channel is a prominent area to watch rare, endemic dolphins, and the less-studied pygmy right whales.