12 Fascinating Facts About the Amazon River

Amazon River, Near Belem
Ricardo Lima / Getty Images

The Amazon River is unparalleled to any other river on Earth. The massive volumes of water the Amazon carries 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, the Amazon's geologic past, unique wildlife, and impact on human history make this river one of the most fascinating places on Earth.

1. The Amazon River Used to Flow in the Opposite Direction

Between 65 and 145 million years ago, the Amazon River flowed towards the Pacific Ocean, in the opposite direction it flows today. Where the Amazon River's mouth sits today, there was once a highland that allowed for this westerly flow. The rise of the Andes Mountains in the west forced the Amazon River to reverse course.

2. It's the Largest River in the World by Volume

Large by volume, Amazon River

CIFOR / Flickr / CC BY-NC-ND 2.0

The Amazon River has the largest volume of freshwater of any river in the world. The River releases around 200,000 liters of freshwater into the ocean every second. Together, this freshwater flow accounts for nearly 20% of all river water that enters the sea.

3. And the Second Longest River on Earth

At about 4,000 miles long, the Amazon River is the second-longest river in the world. The Amazon's impressive length is exceeded by the 4,132 mile-long Nile River. Behind the Amazon, the next-longest river is the Yangtze River, which is only about 85 miles shorter than the Amazon.

4. It Affects Sea Level in the Caribbean Sea

The Amazon River releases so much freshwater into the Atlantic Ocean, it alters sea level in the Caribbean. As freshwater leaves the mouth the Amazon, it gets picked up by the Caribbean Current, which carries the water to the Caribbean islands. On average, models predict the Amazon River alone causes sea levels around the Caribbean to be around 3-cm higher than they would be without the Amazon's freshwater contributions.

5. It's Home to the Amazon River Dolphin

A pink Amazon River dolphin with it's head out of the water.
The Amazon River dolphin is one of just a few river dolphins on Earth.

Michel VIARD / Getty Images

The Amazon River Dolphin (Inia geoffrensis), also known as the pink river dolphin or boto, is one of just four species of "true" river dolphins. Unlike their ocean-dwelling counterparts, river dolphins live exclusively in freshwater habitats. Based on a fossilized dolphin discovered in Peru's Pisco Basin, the Amazon River Dolphin is estimated to have evolved about 18 million years ago.

While the Amazon River dolphin is quite abundant in the waters of the Amazon and Orinoco rivers, it is currently considered an endangered species due to recent population declines resulting from a number of human activities. Populations of the Amazon River dolphin are particularly hurt by the damming and pollution of the Amazon River. The dolphins are also killed by fishermen for use as bait to catch catfish. In recent years, fisherman have switched from catching the "capaz" catfish (Pimelodus grosskopfii) to the "mota" (Calophysus macropterus), the latter of which is easily attracted by Amazon River dolphin bait.

6. The Dorado Catfish Also Lives Here

The dorado catfish (Brachyplatystome rousseauxii) is one of six species of "goliath" catfish found in the Amazon River. Like the capaz and mota catfishes, the goliath catfishes are commercially important species, with the dorado catfish being perhaps the most important of all of the Amazon's catfish. The dorado catfish can grow to be over six feet long and migrates over 7,200 miles to complete its life cycle.

7. It's Named After a Greek Myth

The Amazon River and the Amazon Rainforest were named by Francisco de Orellana, the first European explorer to reach the area, after he encountered the indigenous Pira-tapuya people. In a battle against de Orellana and his men, Pira-tapuya men and women fought alongside one another. According to Greek mythology, the "Amazons" were a group of nomadic female warriors that roamed around the Black Sea. While partially fictitious, the myth of the Amazons is based on the Scythians, a group known for being masters at horseback riding and archery. While the Scythians were not a society of all women, as the Greek myth describes, women in Scythian society joined men in hunting and in battle. Based on this mythology, it is thought that de Orellana named the river "the Amazon" after his batter with the Pira-tapuyas, likening the women of the Pira-tapuya to the Amazons of Greek mythology.

8. A Family Canoed to the Amazon River from Canada

In 1980, Don Starkell and his two sons, Dana and Jeff, left Winnipeg on a canoe towards the Amazon River. Jeff abandoned the trip when they reached Mexico, but Don and Dana ventured on. Nearly two years later, the father-son duo reached the Amazon River. By the end of the trip, they had canoed over 12,000 miles.

9. It Has Over 100 Dams

According to a 2018 study, the Amazon River's Andean headwaters have 142 dams, with an additional 160 dams proposed for construction. The dams provide electricity in the form of hydropower but hurt the ecology of the Amazon River system. Fishermen in Brazil's portion of the Amazon River, the Madeira River, already report negative effects on the system's fish, which scientists attribute to the installation of hydroelectric dams.

10. But No Bridges

Passenger transport - speed boat at sunrise in the Amazon
A speed boat is the only means of transport across the river. Image by Ramesh Thadani / Getty Images

All 10 million people who live on the banks of the Amazon River can only cross the freshwater flow by boat. The lack of bridges is due, in part, to the seasonal changes in the Amazon River bed. During the rainy season, the Amazon River can rise over 30 feet, tripling the width of the River in some places. The Amazon's soft river banks erode as with the seasonal inundation of rainwater, making previously sturdy areas into unstable floodplains. Any bridge to cross the Amazon River would need to be incredibly long to have sure footing. There are also few roads connecting to the Amazon River, with the Amazon River itself used for most people's transportation needs.

11. It Crosses Through Four Countries

The Amazon River passes through Brazil, Columbia, Peru, and Venezuela, with Brazil holding by far the largest portion of the River. The Amazon River's watershed, or the areas where it receives freshwater from, includes even more countries. Rainfall in Bolivia, Columbia, Ecuador, Peru, and Venezuela also supplies the Amazon River with much of its freshwater.

12. It's Where 40% of All Water in South America Ends Up

An aerial view of the Amazon River with water levels high, creating islands within the river.
During the rainy season, the Amazon River floods its banks, dramatically expanding the size of the River.

Kevin Schafer / Getty Images

The Amazon River's height rises substantially in the rainy season because around 40% of all of South America's water ends up in the River. Like a wide net, the Amazon River watershed collects rainfall from miles around the Amazon River, including the Andes Mountains and the Amazon Rainforest.

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