Londonderry is an island in Tierra del Fuego

Tierra del Fuego

Tierra del Fuego is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of a main island Isla Grande de Tierra del Fuego divided between Chile and Argentina with an area of , and a group of smaller islands including Cape...

 in Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

 at the western end of the Beagle Channel

Beagle Channel

thumb|right|300px|Aereal view of Beagle Channel. The Chilean [[Navarino Island]] is seen in the top-right while the Argentine part of [[Isla Grande de Tierra del Fuego]] is seen at the bottom-left....

 and Darwin Sound

Darwin Sound

The Darwin Sound is an expanse of seawater which forms a westward continuation of the Beagle Channel and links it to the Pacific Ocean at Londonderry Island and Stewart Island, not far from the southern tip of South America...

; the captain of HMS Beagle

HMS Beagle

HMS Beagle was a Cherokee-class 10-gun brig-sloop of the Royal Navy. She was launched on 11 May 1820 from the Woolwich Dockyard on the River Thames, at a cost of £7,803. In July of that year she took part in a fleet review celebrating the coronation of King George IV of the United Kingdom in which...

, Robert FitzRoy

Robert FitzRoy

Vice-Admiral Robert FitzRoy RN achieved lasting fame as the captain of HMS Beagle during Charles Darwin's famous voyage, and as a pioneering meteorologist who made accurate weather forecasting a reality...

, was a descendant of the Marquis of Londonderry. Politically, the island is located in the Commune of Cabo de Hornos, which belongs to the Magallanes y la Antártica Chilena Region

Magallanes y la Antártica Chilena Region

The XII Magallanes and Antártica Chilena Region is one of Chile's 15 first order administrative divisions...

, Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

. It has an area of 591 km².
The highest point of the island is at 1548 metres. It has an area of 643 km² (248.3 sq mi).

Nearby islands include Gilbert Island and Stewart Island to the northwest, O'Brien Island to the north, and Thompson Island to the east.