How Long is the Amazon River?

By Magazine Team Last updated May 2, 2025 756 0

Contents

1 The Length of the Amazon River

2 Water Volume and Discharge

3 The Source and Mouth of the Amazon River

3.1 Main Outlets

4 The Amazon Basin

4.1 Water Runoff

5 Environmental Concerns

5.1 Dams and Hydropower

6 Conclusion

7 References

The Amazon River is unlike any other river on Earth. Its massive volumes of water feed the adjacent Amazon rainforest, make it impossible to build bridges over, and even raise the height of the ocean in the Caribbean Sea. In addition to the Amazon River’s role as a global freshwater powerhouse, its geologic past, unique wildlife, and impact on human history make this river one of the most fascinating places on Earth.

The Length of the Amazon River

How long is the Amazon River? It seems like a simple question, but the truth is that this has been plaguing scientists, explorers, and geographical societies for decades. The answer is far from straightforward due to various factors that complicate the measurement of a river.

The Amazon is approximately 6,800 kilometers (4,225 miles) long, making it the longest river in the world. This measurement surpasses the Nile River, which is about 6,695 kilometers (4,158 miles) long. However, the debate over the exact length of the Amazon continues, with some researchers claiming it could be longer than currently accepted figures based on different measurement techniques and criteria.

Water Volume and Discharge

Not only is the Amazon the longest river, but it is also the largest in terms of the quantity of water it transports. The river contains more water than the Mississippi, Nile, and Yangtze combined. In fact, it delivers an astonishing 55 million gallons of fresh water into the Atlantic Ocean every second, equating to 17 billion metric tons every single day. This immense volume translates to the amount of freshwater used by New York City every nine years!

To put this into perspective, the Amazon discharges more freshwater than the next seven largest rivers combined. This volume is so significant that it accounts for one-fifth of all the freshwater in the world’s oceans. Remarkably, even a hundred miles out into the Atlantic, you could still drink the water over the side of your ship, showcasing the river’s influence on ocean salinity.

The Source and Mouth of the Amazon River

The Amazon River is born in the Apacheta ravine , located on the slopes of the Nevado Quehuisha in Arequipa, Peru. The Apacheta stream flows through a series of tributaries, including the Cacansa River and later the Sillanque River, before it makes its way to the Atlantic Ocean.

Main Outlets

At its mouth, the Amazon has three main outlets to the Atlantic Ocean: two on the northern side of Marajó Island in Brazil and one to the island’s south, which joins the Pará River . Scientists typically select one of the northern outlets for measurement, as the Pará is an estuary of the Tocantins River, which is technically separate from the Amazon.

The Amazon Basin

The vast Amazon basin, known as Amazonia , is the largest lowland in Latin America, covering an area of about 2.7 million square miles (7 million square kilometers) . This area is nearly twice as large as that of the Congo River, the Earth’s other great equatorial drainage system. The basin stretches approximately 1,725 miles (2,780 kilometers) from north to south at its widest point and includes significant portions of Brazil, Peru, Colombia, Ecuador, Bolivia, and a small area of Venezuela.

Water Runoff

It is estimated that about one-fifth of all the water that runs off Earth’s surface is carried by the Amazon. The flood-stage discharge at the river’s mouth is four times that of the Congo and more than ten times the amount carried by the Mississippi River. This immense volume of freshwater dilutes the ocean’s saltiness for more than 100 miles (160 kilometers) from shore, significantly impacting marine ecosystems.

Environmental Concerns

Dams and Hydropower

According to a 2018 study, the Amazon River’s Andean headwaters have 142 dams, with an additional 160 dams proposed for construction. While these dams provide electricity through hydropower, they pose significant threats to the ecology of the Amazon River system. Fishermen in Brazil’s portion of the Amazon River, particularly in the Madeira River, have reported negative effects on fish populations, which scientists attribute to the installation of hydroelectric dams. These developments not only impact local wildlife but also disrupt the livelihoods of communities that rely on the river for fishing and transportation. The construction of dams alters water flow, affects sediment transport, and changes the natural habitat, leading to a decline in biodiversity.

Conclusion

The Amazon River is a remarkable natural wonder that plays a crucial role in the Earth’s ecosystem. Its length, immense water volume, and extensive basin make it a vital resource for both the environment and human populations. However, as development pressures increase, it is essential to balance the need for energy and infrastructure with the preservation of this irreplaceable river system. Understanding how long the Amazon River truly is may be a complex question, but its significance is undeniably profound.