The 10 Longest Rivers in South America

January 2, 2024

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Amazon river, one of the longest in South America

South America is home to hundreds of rivers, including the world-famous Amazon River. These rivers provide a source of food, water and transport for millions of people, as well as numerous species of fish, mammals and reptiles.

We’ve compiled a guide to the ten longest rivers on the continent. Continue reading if you want to find out more about these majestic waterways and the areas they flow through!

1. Amazon River – 6,400 km

The Amazon River, looking across to a grassy bank with palm trees and red-roofed huts
Amazon River flowing next to palm trees and houses

Although it’s only the second longest river in the world, the Amazon holds the title of South America’s longest river. It flows through Brazil, Venezuela, Peru and Columbia, where approximately 10 million people live on its banks.

It’s estimated 40% of South America’s water ends up in the Amazon. The river’s discharge water volume is the largest in the world at 215,000–230,000 m3/s, which is even more than the Nile!

The Amazon River has nearly 150 hydropower dams that generate electricity for local communities. However, the dams have proven to harm the ecosystem of the river as they block fish migration routes. These dams also prevent the flow of sediments and nutrients, which has a major impact on the overall health of the river.

Green anacondas, piranhas and pink river dolphins are just some of the wildlife found in the river. In total, there are over 40,000 different plant species, 3,000 fish species and 370 reptile species found in and around the Amazon.

2. Río de la Plata River-Paraná-Rio Grande River – 4,880 km

Image of a tree at dusk, overlooking the Paraná River. A wooden bridge is visible in the background
Paraná River flowing past a tree-lined bank

Flowing 4,880 kilometers through Brazil, Paraguay, and Argentina, the Río de la Plata is the second-longest river in South America. The river merges with the Paraguay River in Argentina and eventually the Uruguay River to create the Río de la Plata, which empties into the Atlantic Ocean.

The river has a drainage basin of approximately 2,800,000 square km, which covers part of southeastern Brazil, Paraguay, southeastern Bolivia, and northern Argentina.

The forested region called the Alto Paraná Atlantic Forest is located in the upper Paraná region. Nearly 50% of the amphibians and plants found in the forested area are endemic to the region, which means they aren’t naturally found anywhere else. There are various different fish species found in the river, including the Golden Dorado, Vampire Fish and the Pira Pita.

3. Pur̼s River Р3,379 km

Purús River and sloped riverbanks. There is a forest of trees on top of the slopes and small
Purús River flowing past wooden huts on the riverbank

A tributary of the Amazon River, the Purús River flows for over 3,000 kilometers through Brazil and Peru. The river’s wetlands cover approximately 40,000 square kilometers of the total basin area. These areas flood from December to May each year.

For around 1,300 kilometers, the Purús River’s depth is never less than 15 meters. It is one of the most meandering rivers in the world, although it is navigable for most of its course. One of the biggest industries along its route is rubber, which is gathered from the nearby forests.

Much of the Purús River basin is protected to help preserve the threatened species of flora and fauna. The river is lined by numerous national parks and forests that contain animals and reptiles such as the Purús Red Howler monkey, Boa constrictors and green parrots.

4. Juruá River – 3,350 km

A large caiman resting in the shallow water of the Juruá River. The water and banks are a muddy brown
Caiman resting in the shallows of the Juruá River

Yet another tributary of the Amazon River, the Juruá River begins in east-central Peru and travels 3,350 kilometers into Brazil until it joins the Solimões stretch of the Amazon River. The river is navigable for approximately 1,800 kilometers, although the majority of its banks are uninhabited. Most of the river’s tributaries weren’t mapped until they were recorded by satellite in the late 1970s.

Water discharge from the Juruá River accounts for around 2% of the Amazon’s annual discharge. Many Brazilian indigenous communities rely on the river as a source of drinking water and food. There are also government plans to build 80 dams in the near future, which will provide electricity to multiple river communities.

There are around 185 different species of fish in the Peruvian section of the river and approximately 10 types in the Brazilian section. This includes the likes of catfish, piranhas and characins, as well as reptiles such as caimans. Along the river bank and basin, you can also find a variety of birds, such as parrots and kingfishers.

5. Ṣo Francisco River Р3,180 km

Multiple canoes are moored at the banks of the São Francisco river
Canoes docked at the banks of the São Francisco

Beginning in the state of Minas Gerais in southeast Brazil, the São Francisco River flows approximately 3,180 km through Brazil until it meets the Atlantic Ocean. It covers an area of around 636,920 km2.

The river has an average depth of two meters and nearly 170 tributaries that feed into it. It’s estimated that 64% of the fish species that live in the river are endemic. Capybaras, the world’s largest rodent, are also found in and around the river, as are skunks and armadillos.

Along the upper-middle basin, locals predominately grow cotton, rice, beans and corn. The agricultural region also grows sugarcane, pineapples and coffee beans. The river is also an important transport link for Minas Gerais, although the São Francisco is fairly difficult to navigate.

6. Tocantins River – 2,640 km

A man looks at the camera while sailing a boat on the Tocantins River
Boat on Tocantins River

The 2,640-kilometer-long Tocantins River flows through the Brazilian state of Goiás, Tocantins, Maranhão, and Pará. Many people mistake it as a tributary of the Amazon, although the Tocantins actually has its own drainage basin. It begins its journey in the Goiás state and flows directly out into the Atlantic Ocean.

11 indigenous ethnic tribes live in communities along the banks of the river, although this only totals around 14,000 people. Fishing helps provide a source of food for the local people, but this combined with the multiple dams in the river have affected fish populations.

There is rich biodiversity in and around the Tocantins River. Out of the 350 fish species that live in the river, 175 are endemic, including the Pleco catfish and South American killifish. 527 species of birds also live in the areas, as do eight primate species.

7. Japurá River – 2,615 km

An underwater photograph of a catfish swimming near the bottom of a river
Catfish swimming through river

The Japurá River flows 2,615 kilometers through Brazil and Colombia. It begins in the Andes in the Southwest of Colombia as the Caquetá River and flows eastward into Brazil. The Caquetá-Japurá basin is approximately 253,000 km2, which accounts for 3.7% of the Amazon River’s entire basin.

On average, the area experiences about 2,500 mm of annual precipitation. Following the rainfall, the river typically floods. The river is split into two types of water: blackwater and whitewater. The blackwater contains little few suspended solids, whilst the whitewater contains a significant amount.

A vast array of species live in the river, including electric eels, catfish and turtles. The catfish can weigh up to 91 kilograms and grow up to 1.8 meters long!

8. Paraguay River – 2,549 km

Brown and white rowing boat tied up on the Paraguay river bank
Rowing boat moored on the Paraguay river

The Paraguay River runs through Brazil and its namesake country Paraguay. It follows a course of over 2,500 kilometers from the Brazillian state of Mato Grosso before it joins with the Paraná River in Corrientes, Argentina.

Unlike the majority of other great rivers in South America, the Paraguay River does not have dams for hydroelectric power. This means it is navigable for a lengthy distance, which helps enable trade and travel for local people.

The river forms the border between Brazil and Paraguay for 220 kilometers south from Puerto Bahia Negra until it joins with the Apa River. Together with the Paraná and Uruguay Rivers, it also forms the second-largest drainage system in the world. The three rivers cover an estimated 1.6 million square miles and empty at an estimated rate of 2.8 million cubic feet of water per second into the Rio de la Plata estuary.

9. Orinoco River – 2,250 km

An Orinoco Crocodile in the water. Only its eyes and part of its snout are visible above the green water
Orinoco Crocodile head above water

Located in Venezuela and Brazil, the Orinoco River flows 2,250 kilometers which makes it the ninth longest river in South America. However, in terms of water discharge volume, the Orinoco is the fourth-largest river in the world. The river has a discharge rate of 33,000 m³/s.

Beginning on Mount Delgado Chalbaud in Venezuela, the river flows in a northwestern and western direction through the mountainous region until it reaches the Guaharibo Rapids. It then changes direction towards the west. Part of the river makes up the border between Colombia and Venezuela.

As one of the most important waterways in South America, the Orinoco River provides a busy route for imported and exported goods. Ships from the ocean are able to travel inland for around 270 miles via the river.

Many of the different species that live in and around the river are endangered or threatened. This includes the Orinoco crocodile, which is endemic. Over 1,00 different species of fish are also found in the depths of the Orinoco.

10. Mamor̩ River Р1,930 km

a person driving a boat on the Madeira river. He is silhouetted against the sunset
Boat on the Madeira River at sunset

Flowing through Bolivia and Brazil, the Mamoré River stretches 1,930 kilometers until it joins with the Beni River to form the Madeira River (the Amazon’s largest tributary). Multiple indigenous communities live on the banks of the river, as do over 700 animal species and over 400 types of vegetation.

The increased human population in the Mamoré River basin has led to falling numbers of local species, including the Bolivian River Dolphin. This is a direct result of hunting and entanglement in fishing nets. The proposed dams in the Madeira River could also affect aquatic life in the Mamoré River.

Due to the rapids near its junction with the Beni River, it’s difficult to navigate and use the Mamoré River as a trade route. However, the river is navigable through the Moxos plain and tropical rainforests to the towns of Guajará-Mirim in Brazil, and Guayaramerín in Bolivia.

Overview: Longest rivers in South America

RankRiver systemCountryLength (km)Length (miles)Outflow
1Amazon RiverPeru, Colombia, Brazil6,4003,977Atlantic Ocean
2Rio de la Plata RiverArgentina, Uruguay4,8803,032Atlantic Ocean
3Purus RiverBrazil, Peru3,3792,100Amazon River
4Jurua RiverBrazil, Peru3,3502,082Amazon River
5Sao Francisco RiverBrazil3,1801,976Atlantic Ocean
6Tocantins RiverBrazil2,6401,640Atlantic Ocean
7Japura RiverBrazil, Colombia2,6151,625Amazon River
8Paraguay RiverParaguay, Brazil, Argentina, Bolivia2,5491,584Parana River
9Orinico RiverColombia, Venezuela2,2501,398Atlantic Ocean
10Mamore RiverBrazil, Bolivia1,9301,199Amazon River

Of the hundreds of rivers in South America, the Amazon is by far the longest. It flows through four countries and sustains the livelihood of 10 million people. Some of the Amazon’s tributaries also feature on this list, such as the Purús and Juruá rivers.

South America’s rivers and basin areas have a rich biodiversity. Hundreds of different reptile, fish and mammal species live in and around the rivers. This includes many endemic species, such as the critically endangered Orinoco crocodile.

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