The Isla de los Estados Provincial Reserve is located in the extreme south of Argentina, in the Province of Tierra del Fuego and South Atlantic Islands, separated from the Isla Grande de Tierra del Fuego by the Le Maire Strait, about 30 km wide. The body of the island is formed by a mountain range, which can be considered the southeastern end of the Fuegian mountain range. What is known as Isla de los Estados is a group integrated by Isla de los Estados itself, the Año Nuevo archipelago, and several smaller islands and islets that rise at a short distance. Observatory Island is the largest and highest of the islands of the Año Nuevo group, which is why it was the site chosen to erect a lighthouse at the beginning of the 20th century. Giant petrels, imperial cormorants and black-headed cormorants nest there. The rest of the Año Nuevo group is formed by Elizalde, Alférez Goffré and Zeballos Islands. The relief of Isla de los Estados, as well as the different small islands, is very varied, with irregular and rugged coasts that form abundant fjords, coves and bays. It is worth mentioning that it is the only place in Argentina where there are fjords.

Isla de los Estados and Le Maire Strait have been identified as relevant areas for the conservation of marine biodiversity and constitute the main breeding area of the southern yellow-plumed penguin, representing 26% of the world population of this subspecies. This area has been cited as an important seabird breeding site. The area is also home to colonies of diving petrels, Magellanic penguins, southern giant petrels, imperial and black-headed cormorants, South American terns, skuas, and black-browed albatrosses, among others.