Portugal's geography: a country measured mostly in ocean

How Portugal counts what it owns

There are three defensible answers to the question of how large Portugal is, and the difference between them is not rounding. The land measures 92,225 square kilometres, and Eurostat published a geographical size of 92,226 square kilometres in its 2025 figures. Portuguese law defines the country as 156,597 square kilometres, because that definition counts about 64,000 square kilometres of internal waters and territorial sea as territory. The exclusive economic zone, over which Portugal holds rights to the exploration and use of marine resources, extends to 1,727,408 square kilometres.

The zone arrives in three pieces, one around the mainland and one around each archipelago, and the arithmetic between them is the point.

The Azorean component is close to three times the continental one. Nine inhabited islands with a combined coast of 667 kilometres therefore carry more sea rights than the whole of the mainland. Most of the country's measurable extent is Atlantic, and the archipelagos hold it.

On land the border is a single line of 1,215 kilometres, shared with Spain and with nobody else. One section of it is not agreed. Portugal does not recognise the frontier between the Caia and the Ribeira de Cuncos, following the occupation of Olivenza by Spain that began in 1801, and the territory is administered by Spain. This catalogue records that the section is disputed and takes no position on it.

Beneath the water the continental shelf covers 28,000 square kilometres and narrows as it runs south, from about 150 kilometres wide off the north coast to about 25 kilometres off the south. Deep submarine canyons cut across it, continuing the courses of the main rivers, and the continental slope runs up against the Gorringe Bank in the south. The Portuguese government claims jurisdiction to a sea depth of 200 metres, or to the depth of exploitation.

Why the Tagus divides the mainland

Continental Portugal is a low country with high ground at one end. More than 70% of the territory lies below 400 metres and less than 12% rises above 700 metres, and the mainland occupies about one sixth of the Iberian Peninsula, on its Atlantic edge.

The Tagus is the line the two halves fall on. It enters from Spain, runs northeast to southwest and opens into an estuary at Lisbon, and 95% of all Portuguese land above 400 metres sits north of it. South of the river, across the Alentejo and the Algarve, 62% of the ground lies below 200 metres, and a single southern range, the São Mamede, passes 1,000 metres.

North of the Tagus the country is plateau, faulted and cut by entrenched river valleys. In the Minho the mountains form an amphitheatre facing the Atlantic, topped by the Larouco at 1,527 metres, built of crystalline schists, slates and quartzites with granite intrusions, and the fault lines there produce hot springs. Beyond them, in Trás-os-Montes, the high plateaus of the terra fria, the cold country, sit at 600 to 800 metres on Precambrian granite and schist. South of the Douro the same rock produces the opposite effect: sheltered valleys of dark schist trap the heat and are called the terra quente, the hot country. The Estrela Mountains, which carry Torre at 1,993 metres, are the Portuguese continuation of the Central Sierras of Spain.

The south is the flat half. Three fifths of all Portuguese land below 400 metres lies there. Triassic sandstones run from the lower Douro down to Lisbon and the lower Tagus, descending to low, sometimes marshy coasts; inland from Leiria, Jurassic limestones and younger Cretaceous sandstones have eroded into rolling sandy hills and steep calcareous escarpments. The Alto Alentejo is a continuation of the Spanish tablelands at 180 to 400 metres, with poor soils except where diorite outcrops have weathered into rich black earth. Further south the ridges of quartz and marble of the Baixo Alentejo undulate between 90 and 180 metres, ending in the schist of the Caldeirão at 577 metres, and the Monchique massif of intrusive syenite reaches 902 metres at Mount Foia. Most Portuguese soil is acidic, sandy and dry, and outside the wetter north and the alluvium of the main river valleys it does not support intensive cultivation without irrigation.

Why every large river arrives from Spain

Every one of the main rivers is Spanish before it is Portuguese. The Minho, the Douro, the Tagus and the Guadiana all rise in the Meseta, the block of ancient rock at the core of the peninsula, and cross into Portugal over its edge through a series of defiles. That entry is the reason they are poor routes inland: a river that arrives through a gorge is difficult to navigate and difficult to lay a road or a railway beside.

The Douro shows what that costs. It runs about 300 kilometres inside the country, and in its upper reaches the bed drops five metres per mile through gorges 30 to 50 metres deep. It has been made navigable from near Porto up to the Spanish frontier only because locks were built into five dams, one of them 35 metres high. The Guadiana turns south rather than west, reaching the Gulf of Cádiz, and forms part of the frontier on the way, as the Minho does in the north.

The longest river contained entirely within Portugal is the Mondego, 220 kilometres from its source in the Estrela Mountains to the sea, and like the Vouga, the Sado and the Zêzere it is navigable only for short distances. Regular flooding in the lower Tagus lays down the silt that makes the campo good farmland, and the same floods turn severe when strong southerly gales drive high seas up the estuary against the outflow.

Continental Portugal has no large natural lake. The biggest inland water surfaces are reservoirs, of which the Alqueva runs 83 kilometres in length and covers 250 square kilometres. The natural fresh water is small and scattered: Lagoa Comprida and Lagoa Escura in the Estrela, both left by ancient glaciers, and the Pateira de Fermentelos near Aveiro. In the Azores the lakes sit in the calderas of extinct volcanoes, among them the Lagoa do Fogo and the twin Lagoa das Sete Cidades on São Miguel.

What the coast is made of

The mainland coast runs 943 kilometres, four fifths of it facing west, and it is notably unindented. Except at the mouths of the larger rivers there are few natural harbours, and Portuguese ports have been built where the geology allowed rather than where trade wanted them. The two natural ones are Lisbon, on the Tagus, where a long narrow deepwater channel opens into a broad expanse of inland water, and Setúbal on the Sado. The rest depend on the shelter of a headland or on breakwaters, as at Leixões and Sines.

Two lagoon systems interrupt the line. The Ria de Aveiro is a delta about 45 kilometres long and up to 11 kilometres wide, with four main channels threading between islands and islets at the mouths of the Vouga, the Antuã, the Boco and the Fontão. Narrow headlands closed it into a lagoon from the sixteenth century, which is what allowed salt production there; Roman forces had already exported salt from the same coast to Rome. In the Algarve the Ria Formosa encloses sandy islands, and the same province ends at Cape St Vincent in steep cliffs.

The water off the west coast behaves differently from the water off the south. Upwelling brings nutrients to the surface along the western shore, and the same process drives the Nortada, the northerly wind that blows along the coast through the summer. The south coast sea surface runs from 15.5 to 16 °C in January to 21 to 23 °C in August; the west coast holds between 14 and 16 °C in winter and 18 and 20 °C in summer. Tidal gauges have measured a sea level rise of 1 to 1.5 millimetres, enough to push some large estuaries over their banks.

The beaches follow the rock. The mainland alternates cliff and fine sand, the Azores are black sand and boulders, with white sand appearing only as an exception at Almagreira on Santa Maria, and Porto Santo in the Madeira group carries a dune beach of a kind the mainland has nowhere.

How the Azores and Madeira were built

How the Azores sit on three plates

Nine volcanic islands make up the Azores, spread over 650 kilometres in three groups, running from west to east as Flores, Corvo, Faial, Pico, São Jorge, Graciosa, Terceira, São Miguel and Santa Maria, with the Formigas rock outcrops between the last two. They straddle the Mid-Atlantic Ridge at the junction of the African, European and North American plates. Santa Maria, the easternmost, lies 1,408 kilometres from the mainland; Flores, the westernmost, is about 1,980 kilometres from Cape Race in Newfoundland.

The volcanism has not stopped. Capelinhos formed off the western coast of Faial in 1957 and 1958, and submarine volcanoes such as the Dom João de Castro Bank have erupted within recorded history, as did the Serrata eruption off Terceira. Seismic events are common. Rainfall is heavy but most streams are temporary: the catchments are small, the slopes steep, and forest clearance has made the rivers torrential during intense rain. Tropical cyclones reach the islands from time to time, Hurricane Jeanne in 1998 and Hurricane Gordon in 2006 among them.

Madeira sits on the African plate and is a different shape of island. Britannica counts eight volcanic islands in the group, about 1,000 kilometres southwest of the mainland, of which only Madeira and Porto Santo are inhabited; the Desertas and the Savage Islands are not. Madeira itself is an asymmetrical mountainous hump rising to 1,862 metres, with roughly a third of its surface above 1,000 metres. Thick basalt layered with beds of ash and scoriae gives it a stepped relief cut into gorges, one of them the crater of Curral das Freiras at about 690 metres deep. Porto Santo, by contrast, is low and flat.

What the seafloor did to Lisbon

The plate boundary that made the islands also destroyed the capital. On the morning of 1 November 1755 a series of earthquakes killed an estimated 60,000 people in Lisbon alone and demolished about 12,000 dwellings; because it was All Saints' Day, much of the population was at mass when the churches came down. Modern research locates the main seismic source in faulting of the seafloor along the tectonic plate boundaries of the mid-Atlantic.

The waves that followed record the reach of that boundary. The tsunami stood about 6 metres high at Lisbon and about 20 metres at Cádiz in Spain, travelled 6,100 kilometres west to Martinique in ten hours and arrived there 4 metres above mean sea level, and damage was reported in Algiers, 1,100 kilometres to the east. The boundary between Eurasia and Africa runs along the Azores-Gibraltar fracture zone, and since the late Oligocene the Iberian plate has moved as part of the Eurasian one.

Why one climate does not cover the country

Five Köppen classes are needed for a territory of this size. The hot-summer Mediterranean class, Csa, covers most of the land south of the Tagus, the inland Douro valley, the eastern Azores and Madeira. The warm-summer variant, Csb, holds north of the Tagus and along the Costa Vicentina in the south west. Most of the Azores are humid subtropical, Cfa. A small area of inland Alentejo is semi-arid, BSk. The Savage Islands are arid, BWh, and are the only Portuguese territory that is.

Average annual temperature runs from 12 to 13 °C in the mountainous interior of the north to 17 to 19 °C in the south, with Funchal at about 20 °C. The official extremes are −16 °C, recorded at Penhas da Saúde on 4 February 1954 and at Miranda do Douro, and 47.4 °C, recorded at Amareleja in the Alentejo on 1 August 2003. Higher and lower readings exist in the record and are not accepted: 50.5 °C at Riodades on 4 August 1881 and 70 °C at Figueira da Foz on 6 July 1949 in an apparent heat burst, both discounted because the enclosures they were taken in were exposed to solar radiation or were sheltered gardens that heat far more than open ground.

Rainfall varies more than temperature. A few mountain tops in the north, in the Peneda-Gerês, take around 3,000 millimetres a year; inland parts of the Alentejo take around 450. On Pico the higher ground takes upwards of 5,000 millimetres, and the Savage Islands around 200. Sunshine runs between 2,300 and 3,200 hours a year, four to six hours a day in winter and ten to twelve in summer. The mechanism behind the seasons is the latitudinal shift of the jet stream: in winter it moves south and the polar front brings the cold and the rain, and in summer it moves north and the Azores High settles over the country.

Who owns the Portuguese forest

Forest covered 39.0% of mainland Portugal in 2017, or 3,472,459 hectares, and almost none of it belongs to the state. About 85% is privately owned, 3% is state property and the remaining 12% is communal land held by local communities. That ownership pattern is the single most consequential fact about Portuguese forestry, because it decides who can be required to clear undergrowth and who decides what gets replanted.

Native species make up 72% of the forested area of continental Portugal: holm oak, cork oak, stone pine and maritime pine. Cork is counted among the country's natural resources alongside fish, tungsten, iron ore, uranium ore, marble, arable land and hydroelectric power. Eucalyptus is concentrated in the Beira region, in Baixo Vouga and Beira Interior Sul. Over a quarter of the plant species now growing in continental Portugal are exotic.

Trees are lost as well as planted. Dutch elm disease, caused by the fungus Ophiostoma ulmi and spread by the elm bark beetle, has been killing European elms since 1920. The elm was planted along the Avenida da Liberdade in Lisbon and known in the countryside as the negrilho, and it is now uncommon as a mature tree anywhere in Portugal.

A land use estimate from 1993 put arable land at 26%, permanent crops and permanent pasture at 9% each, forest and woodland at 36% and everything else at 20%. A more recent accounting describes the country as over two thirds wilderness, almost a quarter agricultural, and the remainder settlement.

Where Portugal has set land aside

The protected estate is one national park, thirteen natural parks, nine nature reserves, five natural monuments and six protected areas, and almost a quarter of the land area falls inside the Natura 2000 network. The single national park is the Peneda-Gerês in the far north, on the Spanish border, which is also where brown bears occasionally appear, near the Minho.

The strongest designation is on Madeira. UNESCO inscribed the Laurisilva of Madeira on 2 December 1999, about 15,000 hectares within the 27,000 hectares of the Parque Natural da Madeira. Laurel forest of this kind is now confined to the Azores, Madeira and the Canary Islands, a relict of a forest type that covered much of southern Europe 15 to 40 million years ago, and about 90% of the inscribed property is believed to be primary forest that has never been felled. It holds at least 76 vascular plant species endemic to Madeira and more than 500 endemic invertebrates, and some of its trees are possibly over 800 years old, which puts their germination before the island was settled. Around 13 liverwort species and 20 moss species in it are recorded as threatened at European scale. Roughly half the property is gazetted under Madeiran law as a strict reserve.

The wetlands are counted separately: 28 Ramsar sites covering 86,581 hectares, alongside seven biosphere reserves, from Paúl do Boquilobo in 1981 to the Berlengas and Santana in 2011. They matter beyond their area because Portugal sits on the East Atlantic Flyway and they serve as wintering and stopover ground for waders moving between Europe and Africa. About 600 bird species have been recorded in the country, of which 235 breed there.

The land mammals belong to the whole peninsula: fox, badger, Iberian lynx, Iberian wolf, Iberian ibex, European wildcat, hare, weasel, Egyptian mongoose and genet. In the rivers the endemism is far higher. Of the freshwater fish species of Portugal and Spain, 73% are found nowhere else, and several of them live in single small lakes.

How fire and drought change the land

Fire is the recurring event in Portuguese land management. Between 2014 and 2024 the country recorded an annual average of 12,496 fires and 112,455 hectares burned. Of the fires recorded in 2024, nearly 30% had an undetermined origin, and arson accounted for almost five sixths of the total area burned that year.

The conditions that carry the fire are the same ones that define the climate: dry acidic soils, a summer under the Azores High with no rain for months, and a forest estate that is 85% privately held and therefore fragmented into parcels with different owners and different clearing regimes. Projections used by Portuguese authorities put average temperatures 3 to 4 °C higher by 2100 than the average of the 1990s to the 2010s, with consequences named for water, ecosystems, agriculture, health and security.

Water is the other half of the same problem. Average rainfall is falling while the number of extremely wet days rises, which produces drought and flood in the same territory in the same year. On the mainland the response has been storage, which is why the largest inland waters are reservoirs. On Madeira the steep gradients and very high rainfall generate flash floods carrying heavy sediment, and on the Azorean islands the small catchments turn torrential within hours.