The Pantanal is the world's largest tropical wetland and largest flooded grassland, a gently sloping basin of the upper Paraguay River that lies mostly in the Brazilian state of Mato Grosso do Sul and extends into Mato Grosso, eastern Bolivia and northern Paraguay. Estimates of its area run from about 140,000 to 195,000 km² (54,000 to 75,000 sq mi), and roughly 80% of its floodplain goes under water in the rainy season. Its protection is patchy but layered: Brazil created the Pantanal Matogrossense National Park in 1981, listed it as a Ramsar wetland of international importance in 1993, and in 2000 UNESCO inscribed four protected areas as the Pantanal Conservation Area World Heritage Site and named a far larger Pantanal Biosphere Reserve. Against that stand up to eight million cattle on private ranches, silt from the surrounding highlands, upstream dams, a long-planned industrial waterway, and the record fires of 2020 and 2024.
Eight million cattle on 2,500 fazendas
The single most important fact about the Pantanal's future is who owns it. About 99% of the land is privately held for agriculture and ranching, divided among some 2,500 fazendas (ranches) running up to eight million cattle. Most species are not yet under threat, because deforestation of native vegetation in the area has been held below 17%, helped by newer regulations. The risk lies in intensification. Erosion and sedimentation from ranching change the soil and the way water moves across the plain, and the shift toward large-scale soybean farming on the surrounding plateaus has brought heavy use of pesticides and fertilisers that leach into the soil or wash down onto the floodplain.
Older pressures are still present too. Logging companies set up during political turmoil drove deforestation to a peak between 1978 and 1989. Hunters and smugglers target reptiles, wild cats and parrots; the hyacinth macaw is endangered largely because of the trade. Commercial fishing concentrates on a few species and is probably unsustainable, while sport fishing on the Paraguay River and its tributaries is the main fishing activity of all. Gold mining and agro-industry add pollution, although water quality across the Pantanal had not been significantly degraded as of 2002, partly because the wetland itself filters chemicals out of the water passing through it.
Silt from the Planalto and the shifting Taquari
The Pantanal is an enormous inland delta. Rivers draining the Planalto highlands to the east drop their sediment as they reach the flat basin, which lies only 80 to 150 m (260 to 490 ft) above sea level and is so gentle that floodwater moves at 2 to 10 cm per second. That makes the wetland very sensitive to what happens upstream. Silt run-off from deforested highlands alters the soil hydrology and is listed as a significant threat.
The Taquari River, a left-bank tributary of the Paraguay that passes the town of Coxim, shows what that means. It is considered the most degraded river in the Mato Grosso do Sul part of the basin. Over recent decades it has repeatedly changed course through avulsions, breaking out through faults and crevasses in its natural levees. The new channels have redistributed huge volumes of sediment and flooded land that used to be farmed, forcing many farmers to abandon the area. Its headwaters are protected by the 30,619-hectare Nascentes do Rio Taquari State Park, created in 1999, but the damage downstream comes from the whole catchment, not just the springs.
The Manso Dam (1999) and the hydropower question
Unlike most large rivers of the Río de la Plata basin, the Paraguay itself has never been dammed for hydropower, which is why it remains navigable for such a long distance. Its tributaries are another matter. The Manso Dam on the Manso River, a tributary of the Cuiabá in Mato Grosso, was proposed after a 1974 Cuiabá River flood left more than 20% of the state capital's population homeless. Construction ran from 1988 to 1999. The dam is 72 m (236 ft) high, holds back a 427 km² reservoir that was full by 2001, and has an installed capacity of 212 MW.
Its side effects are the kind ecologists fear across the upper basin. Between 652 and 1,065 families were displaced, and the vegetation drowned by the reservoir was not cleared first, so its decay lowered dissolved oxygen and harmed fish stocks in and below the dam. Because the Pantanal depends on the timing of its flood pulse, any structure that holds back or releases water on a power schedule changes the rhythm downstream.
The Paraguay–Paraná waterway plan of 1997
The largest infrastructure threat has been a plan rather than a structure. In 1997 the governments of the La Plata basin proposed, through the Hidrovia Intergovernmental Commission, to turn the Paraguay and Paraná rivers into an industrial waterway to cut the cost of exporting soybeans. It involved more dams, dredging, rock removal and channel restructuring, especially on the Paraguay. The proposed dredging would let ocean-going ships travel 3,442 km (2,139 mi) inland, and changing the river's depth and speed could alter the flooding and draining cycle on which the whole wetland depends.
The waterway already exists in a lighter form, running from Cáceres in Mato Grosso to Nueva Palmira in Uruguay. Traffic grew from 700,000 tonnes a year in 1988 to nearly 17.4 million tonnes by 2010 and has since passed 36 million tonnes, mostly soy, then iron ore and fuel. Every increase raises pressure to deepen the channel through the Pantanal itself.
The fires of 2020 and 2024
Fire is the threat that has done the most visible damage. In 2020, a year of severe drought, about 19,890 km² of the Pantanal burned, roughly a quarter of the wetland, killing millions of vertebrates.
Brazil's National Institute for Space Research (INPE) detected more than 21,200 fires in the Pantanal biome up to November 2020, 69% more than in 2005, and 8,106 in September 2020 alone, more than four times the historic average for that month.
2024 began even worse. During the 2023–2024 South American drought, 2,639 fires burned 32,000 hectares in the first two weeks of June alone, six times the previous June record. By 9 July over 760,000 hectares had burned, more than 4% of the wetland, and 3,538 fires had been recorded by 1 July, 40% more than at the same point in 2020. In August a fire started by railway maintenance workers near Corumbá burned more than 17,000 hectares around Porto Esperança, and the federal environment agency IBAMA fined the two companies involved more than R$100 million. The same month Bolivia asked Brazil for help fighting fires, while the Serra do Amolar, in the border zone between the two countries, was also burning.
Climate models point to more of this: more extreme rainfall, longer droughts, and a growing risk that ranch fires used to clear land escape into a drier wetland.
Invasive pigs, golden mussels and jaguar tourism
Two introduced species are now part of the system. Feral domestic pigs have lived in the Pantanal for more than 100 years alongside native collared and white-lipped peccaries; how they compete with the peccaries is still being studied, though jaguars prefer hunting pigs when they are available. The golden mussel, an invasive freshwater mussel that appeared in Argentina around 1990, had spread to Brazil, Bolivia and Paraguay by 2006 and is established in the Paraguay–Paraná system. Tourism adds a quieter pressure: at popular jaguar-viewing spots such as the Encontro das Águas State Park, frequent boat traffic may be altering jaguar behaviour, and reported sightings there have fallen.
From a 1981 national park to a 2000 World Heritage listing
Formal protection began on 24 September 1981, when decree 86.392 created the Pantanal Matogrossense National Park, 135,606 hectares in the municipalities of Poconé and Cáceres in Mato Grosso and Corumbá in Mato Grosso do Sul, with the Cuiabá River running through it. On 24 May 1993 it became a Ramsar site. In 1998 the private SESC Pantanal reserve, 878.7 km² near Poconé, was established and later also listed under Ramsar. Mato Grosso created the 108,960-hectare Encontro das Águas State Park on 22 December 2004 and bans fishing within 2 km of it.
The international step came in 2000. UNESCO inscribed the Pantanal Conservation Area, four protected areas in Mato Grosso and Mato Grosso do Sul, as a natural World Heritage Site, and the same year declared the Pantanal Biosphere Reserve, about 251,569 km² across Goiás, Mato Grosso and Mato Grosso do Sul, which takes in the national park along with Chapada dos Guimarães, Emas and Serra da Bodoquena national parks. Brazil now has the largest area of Ramsar-listed wetland of any country, around 267,000 km² as of February 2025.
Bolivia's share is protected by the Otuquis National Park and Integrated Management Natural Area, 1,005,950 hectares in the far south-east of Santa Cruz Department, entered through Puerto Suárez, together with the San Matías Integrated Management Natural Area.
Set against a wetland of up to 195,000 km², these parks are small islands, which is why the ranches matter so much: most of the Pantanal will only survive if private land keeps flooding and drying on its natural schedule. The same Paraguay River water continues south into Argentina, where it feeds the Paraná Delta; nearby, the Iberá Wetlands show a smaller South American wetland under similar pressures, and the country that shares the Pantanal's southern tip is described in our guide to the geography of Paraguay.