The territory of Portugal includes an area in the Iberian Peninsula (referred to as the continent by most Portuguese) and two archipelagos in the Atlantic Ocean: the archipelagos of Madeira and the Azores. The Portuguese border with Spain forms the second largest international border in the world, second to only the one between The United States and Canada. It lies between latitudes 32° and 43° N, and longitudes 32° and 6° W.
Mainland Portugal is split by its main river, the Tagus that flows from Spain and disgorges in Tagus Estuary, in Lisbon, before escaping into the Atlantic. The northern landscape is mountainous towards the interior with several plateaus indented by river valleys, whereas the south, that includes the Algarve and the Alentejo regions, is characterized by rolling plains.
Portugal's highest peak is the similarly named Mount Pico on the island of Pico in the Azores. This ancient volcano, which measures 2,351 m (7,713 ft) is an iconic symbol of the Azores, while the Serra da Estrela on the mainland (the summit being 1,991 m (6,532 ft) above sea level) is an important seasonal attraction for skiers and winter sports enthusiasts.
The archipelagos of Madeira and the Azores are scattered within the Atlantic Ocean: the Azores straddling the Mid-Atlantic Ridge on a tectonic triple junction, and Madeira along a range formed by in-plate hotspot geology. Geologically, these islands were formed by volcanic and seismic events, although the last terrestrial volcanic eruption occurred in 1957-58 (Capelinhos) and minor earthquakes occur sporadically, usually of low intensity.
Portugal's Exclusive Economic Zone, a sea zone over which the Portuguese have special rights over the exploration and use of marine resources, has 1,727,408 km². This is the 3rd largest Exclusive Economic Zone of the European Union and the 11th largest in the world.