The Ushuaia department in the province of Tierra del Fuego, Antarctica and the South Atlantic Islands comprises the southern sector corresponding to Argentina of the Grande island of Tierra del Fuego, and also the island of the adjacent States and islets. To the north it borders the Tolhuin department and to the west and south it has borders with Chile. To the east it has coasts in the Atlantic Ocean, including the Strait of Le Maire that separates the two main islands of the department. To the south is the Beagle Channel and the sea of the Austral Zone.
Applying the considerations of the International Hydrographic Organization, the Beagle Channel is part of the Pacific Ocean, but the Argentine Government considers it an interoceanic passage not included in any ocean. Its only city is Ushuaia, the southernmost of Argentina and the only one located on the other side of the Andes mountain range, according to the perspective of the rest of the country. Ushuaia rises on the northern margin of the Beagle Channel, at the bottom of a wide bay in the southwest of the department: the bay of Ushuaia. No legal norm has designated a locality head for this department, but in fact fulfills that function the city of Ushuaia. The Beagle Channel is named after the sailboat commanded by its discoverer, Captain Robert Fitz Roy.