continent. Geopolitically, all the island countries and territories in the Caribbean have generally been grouped as a subregion of North America instead. By contrast, Aves Island (administered by Venezuela) and the Archipelago of San Andrés, Providencia and Santa Catalina (San Andrés Island, Providencia Island, and Santa Catalina Island etc., which are administered by Colombia) are politically parts of South American countries but physiographically parts of North America. Other islands often associated with geopolitical South America are the Chiloé Archipelago and Robinson Crusoe Island (both administered by Chile), Easter Island (culturally a part of Oceania, also administered by Chile), the Galápagos Islands (administered by Ecuador, sometimes considered part of Oceania), and Tierra del Fuego (split between Argentina and Chile). In the Atlantic Ocean, Brazil administers Fernando de Noronha, Trindade and Martim Vaz, and the Saint Peter and Saint Paul Archipelago, while the Falkland Islands () and South Georgia and the South Sandwich Islands (biographically and hydrologically associated with Antarctica) have been administered as two British Overseas Territories under the Crown, whose sovereignty over the islands is disputed by Argentina. Special cases An isolated volcanic island on the South American Plate, Ascension Island is geologically a part of South America. Administered as a dependency of Saint Helena, Ascension and Tristan da Cunha, the island is geopolitically a part of Africa. An uninhabited sub-Antarctic volcanic island located in the South Atlantic Ocean, Bouvet Island (administered by Norway) is geographically, geologically, biographically, and hydrologically associated with Antarctica, but the United Nations geoscheme has included the territory in South America instead. Climate All of the world's major climate zones are present in South America. The distribution of the average temperatures in the region presents a constant regularity from the 30° of latitude south, when the isotherms tend, more and more, to be confused with the degrees of latitude. In temperate latitudes, winters and summers are milder than in North America. This is because the most extensive part of the continent is in the equatorial zone (the region has more areas of equatorial plains than any other region.), therefore giving the Southern Cone more oceanic influence, which moderates year round temperatures. The average annual temperatures in the Amazon basin oscillate around , with low thermal amplitudes and high rainfall indices. Between the Maracaibo Lake and the mouth of the Orinoco, predominates an equatorial climate of the type Congolese, that also includes parts of the Brazilian territory.