- Where
- Eastern Algarve coast,
southern Portugal - Coordinates
- 37.03° N
7.81° W (Ramsar site record) - Natural park
- Created by decree of
9 December 1987; 17,900.77 ha (ICNF) - Ramsar site
- No. 212, designated
24 November 1980; 16,000 ha - Audouin’s gull
- More than 7,000 nests
in 2024 (ICNF) - Best visited
- Winter and the migrations (ICNF);
no month band read - Advisory
- Portugal Level 1
Low tide, and half the water had gone and left the mud behind, shining, with rows of wooden stakes in it and people bent double among them, raking. Beyond a strip of sand I could hear the ocean. Long pink legs everywhere, and white birds stepping about as if they owned the place. Behind me the town was all flat white roofs. I took my shoes off without being asked.
The short answer
The Ria Formosa is a coastal lagoon on the eastern Algarve coast of southern Portugal. A belt of sandy beaches and dunes separates it from the Atlantic: from west to east, ICNF lists the Ancão peninsula, the islands of Barreta, Culatra, Armona, Tavira and Cabanas, and the Cacela peninsula, with six tidal inlets between them. Inside lie saltmarsh, sand and mud flats, dunes, salt pans, freshwater and brackish ponds, streams, farmland and pine woods. The lagoon is on average 2 metres deep. ICNF says about 14 per cent of it is always under water and about 80 per cent of its floor emerges at low water on spring tides, and that it is fed almost entirely by the sea, because the streams that run into it are seasonal. Decree-Law no. 373/87 of 9 December 1987 created the natural park, which ICNF gives as 17,900.77 hectares across the municipalities of Faro, Loulé, Olhão, Tavira and Vila Real de Santo António. The lagoon was listed under the Ramsar Convention on 24 November 1980, and it is a Special Protection Area for wild birds in the European Union’s Natura 2000 network.
Why it's worth knowing
A lagoon the tide empties. ICNF’s description of the Special Protection Area calls the Ria Formosa the most important wetland in the south of Portugal, and one of the most important places in the country for migratory birds, especially waders, ducks and seabirds. Many waterbirds from northern Europe, its park page says, spend the winter here or stop over on their way further south. Among the wintering ducks it names mallard, wigeon, shoveler, teal and pochard, and among the waders Kentish, ringed and grey plovers, bar-tailed and black-tailed godwits, curlew, avocet, black-winged stilt, little stint and dunlin. The Key Biodiversity Areas Partnership’s factsheet for the lagoon, last assessed in 2002, says it regularly holds 20,000 or more wintering waterbirds and that its reedbeds draw large numbers of migrating songbirds in spring and autumn. The 1992 Ramsar information sheet calls it a key wintering and stopover site in Portugal for black-tailed godwits, little stints, knots, ringed and Kentish plovers and black-winged stilts.
A lagoon people work. People live along the whole length of the lagoon, ICNF writes, and much of its economy is tied to the water. Clam beds, farmed above all for the grooved carpet shell (amêijoa-boa), cover some hundreds of hectares, their boundaries marked by stakes that show at low tide; shellfish are also gathered from natural beds outside the licensed areas. Salt-making here has a history lost in the distant past, the institute says, and the salt pans still supply an important share of Portugal’s salt; they are also a resting and feeding place for large numbers of waders on the flyway between Europe and Africa, which is why ICNF calls their conservation extremely necessary. As salt-making has declined, fish farms for sea bass, gilthead bream and white seabream have been built in old salt pans. ICNF counts 65 fish species in the lagoon, which serves as a nursery for fish and shellfish. Its seagrass meadows held the largest seahorse population in the world about fifteen years before 2022, ICNF and the CCMAR marine science centre said that year, and the population has since fallen by more than 90 per cent.
The field notes
The swamphen on the badge
The natural park’s symbol is the purple swamphen, Porphyrio porphyrio, called caimão or galinha-sultana in Portuguese. ICNF describes it as a threatened species: its size and showy plumage long made it a target for hunters, while the gradual draining of wetlands destroyed much of its habitat. The park page says its numbers have risen in recent years thanks to growing protection and study. The 1992 Ramsar information sheet already named the Ria Formosa as a key breeding site for the bird, which it calls the purple gallinule, along with little egrets, black-winged stilts, avocets, Kentish plovers, stone-curlews and little terns.
Gulls on a barrier island
Audouin’s gull is declining worldwide, ICNF said in July 2024, but in Portugal it has gone the other way. Since the species settled in the Ria Formosa about a decade earlier its numbers had risen every year, and in 2024 the specialists of the LIFE Ilhas Barreira project counted more than 7,000 nests, nearly three times as many as when the project began in 2019, in what the institute called the largest colony of the species in the world. The main colony is on Ilha Deserta, also called Barreta, and since 2022 the gulls have nested on neighbouring Culatra too. ICNF describes the bird as an elegant gull with grey legs and a red bill that still feeds mostly on fish, including fishing discards, and rarely on rubbish; because it breeds in only a few colonies worldwide, it is vulnerable to predators on land and to human disturbance. The annual count is coordinated by ICNF and the MARE centre at the University of Coimbra, with help from the Portuguese Society for the Study of Birds (SPEA), which leads the project.
Little terns in the dunes
The little tern, a species in decline in Europe, nests in the dunes and salt pans of the Ria Formosa, and ICNF says the lagoon’s birds make up 40 per cent of Portugal’s population. The park also has a little egret colony, white storks, and spoonbills that have nested in some years. The Key Biodiversity Areas factsheet notes that tourists can cause moderately high disturbance locally, especially to beach-nesting birds such as the little tern and the Kentish plover. Birds of prey are not common, ICNF says, but on migration and in winter hen and Montagu’s harriers, buzzards, peregrines and kestrels hunt across the area, and short-eared, barn and tawny owls hunt by night.
A house with no back
Beside the Marim environmental education centre, about a kilometre east of Olhão off the EN 125 road, stands the Chalet João Lúcio, a three-storey manor house of 1916. ICNF describes it as square, with no front and no back, and four entrances, one to each point of the compass, each with a staircase in its own shape: a fish to the north, a guitar to the south, a violin to the east and a serpent to the west, standing for water, fire, air and earth. Its owner, the Olhão lawyer and poet João Lúcio, never lived in it; he died of pneumonia in 1918. The house belongs to ICNF and is now, the institute says, an ecoteca.
August 2019A little egret on the edge of the lagoon at Fuseta.
Photograph: José Prego · Garça-branca-pequena Egretta garzetta, (ria Formosa, Fuzeta, Portugal) (48629901048) · CC BY 2.0
June 2015A shelduck and an avocet on a bank in the Ria Formosa.
Photograph: Roweromaniak · Ria Formosa D8T-26 · CC BY-SA 3.0 · cropped
June 2015A gull resting on salt in a pink salt pan in the Ria Formosa.
Photograph: Roweromaniak · Ria Formosa D8T-03 · CC BY-SA 3.0 · cropped
- Find out when the tide goes out and be there for it, when the mud is bare and every bird is busy.
- The stakes in the mud mark somebody’s clam beds. Walk round them, and leave the shellfish to the people with rakes.
- If a small bird on the beach starts shouting at you, back away slowly. You are standing too near its nest.
- Write the birds on the list as you see them. (The mud has the first page. The second blew out towards the islands, which I have now added to the list.)
- Take a boat out to one of the long sandy islands, and catch a later boat back than you meant to.
The stakes that mark the clam beds. Across the Ria Formosa’s mudflats, ICNF says, shellfish are farmed in beds (viveiros) whose main product is the grooved carpet shell, amêijoa-boa. The beds cover some hundreds of hectares, and at low tide the stakes that mark their bounds stand out of the water. The beds are licensed concessions; gathering shellfish from natural beds, a practice ICNF calls of proven antiquity, is done today outside them.
Tally, in the marginI took the stakes for a fence that had lost its field, and spent most of a low tide wondering what they were keeping out. Only when the water came back over them did I see that they were not keeping anything out at all, just telling each raker where their own patch ended.
Getting there
How to get there. The park’s headquarters and its environmental education centre, the Centro de Educação Ambiental de Marim at Quinta de Marim, are beside the EN 125 road about a kilometre east of Olhão, next to the Olhão campsite, according to ICNF. The institute said in 2020 that the centre, a site of woodland, saltmarsh, dunes, ponds and salt pans, received some 30,000 visitors a year, and the programme for the park’s 2026 open day, published by AMAL, the Algarve’s intermunicipal community, began with a guided birdwatching walk from the centre. The 1992 Ramsar information sheet describes the lagoon as facing Faro, Olhão and Tavira. The official pages read for this entry give no airport, public-transport route or drive time, so we give none here.
When to go. ICNF names the lagoon’s wintering ducks and waders and the birds that stop over on migration; the little terns and Audouin’s gulls nest on the islands, dunes and salt pans, and the institute’s gull count was reported in July. The official pages read give no month band. The 1992 Ramsar sheet notes heavy holiday pressure on the area from June to September. ICNF describes the climate as Mediterranean and semi-arid, with a long dry summer, a mild winter, and averages of about 450 millimetres of rain, 18°C and 3,150 hours of sunshine a year.
What to arrange ahead. The official pages read for this entry give no opening hours or prices for the Marim centre, and we have not used other sites’ figures. AMAL’s 2026 open-day programme listed boat trips into the lagoon run by several private operators from Faro and Olhão; we name none.
Access. Most of the wetland and seashore is public land owned by the state, the 1992 Ramsar sheet says, while the salt pans, many of the fish farms and most of the farmland are private. The clam beds are licensed areas, ICNF says. The Key Biodiversity Areas factsheet records disturbance of beach-nesting birds by visitors, and ICNF says Audouin’s gulls are vulnerable to human disturbance at their colonies. The official pages read give no visitor rules for the barrier islands.
Safety. The US State Department has Portugal at Level 1, exercise normal precautions (advisory dated 23 December 2025), and asks travellers to stay alert to petty theft, particularly in crowded tourist areas and on public transport.
Mark this place
Common questions
What birds is the Ria Formosa known for?
The Ria Formosa lagoon in the Algarve, Portugal, is known for wintering ducks and waders from northern Europe, ICNF says, and for its breeding birds: the purple swamphen, the park’s emblem; little terns, 40 per cent of Portugal’s population; and more than 7,000 Audouin’s gull nests counted in 2024.
Where is the world's largest colony of Audouin's gulls?
ICNF, Portugal’s nature conservation institute, says the largest Audouin’s gull colony in the world is in the Ria Formosa, on Ilha Deserta (Barreta), with a newer colony on Culatra since 2022. In 2024 the LIFE Ilhas Barreira project counted more than 7,000 nests there.
What is the symbol of the Ria Formosa Natural Park?
The symbol of the Ria Formosa Natural Park in Portugal is the purple swamphen, Porphyrio porphyrio, known locally as caimão or galinha-sultana. ICNF describes it as a threatened species, once hunted for its size and plumage, whose numbers in the park have risen in recent years.
How many waterbirds winter in the Ria Formosa?
The Key Biodiversity Areas Partnership’s factsheet for the Ria Formosa in Portugal, last assessed in 2002, says the lagoon regularly holds 20,000 or more wintering waterbirds, especially waders and ducks, and that its reedbeds draw large numbers of migrating songbirds in spring and autumn.
Is the Ria Formosa a Ramsar site?
Yes. The Ria Formosa in the Algarve is Ramsar site no. 212, designated on 24 November 1980 with an area of 16,000 hectares. Its Ramsar record calls it important for numerous breeding, wintering and staging waterbirds, including egrets and ibis; it is also a natural park and a Special Protection Area.
How big is the Ria Formosa Natural Park?
ICNF gives the Ria Formosa Natural Park in Portugal an area of 17,900.77 hectares, stretching along the Algarve coast from Ancão to Manta Rota across five municipalities. The lagoon averages 2 metres deep, and about 80 per cent of its floor emerges at low water on spring tides.
Where is the Ria Formosa visitor centre?
The Ria Formosa Natural Park’s environmental education centre is at Quinta de Marim, beside the EN 125 road about a kilometre east of Olhão, next to the park’s headquarters, according to ICNF. In 2020 the institute said the centre received some 30,000 visitors a year.
Do little terns nest in the Ria Formosa?
Yes. ICNF says the little tern, a species in decline in Europe, nests in the dunes and salt pans of the Ria Formosa in the Algarve, and that the lagoon’s birds make up 40 per cent of Portugal’s population. Visitors can disturb beach-nesting birds, the Key Biodiversity Areas factsheet notes.
What to pack: the Small islands & boats kit, warm seas, little shade