Humanities › Geography Amazon River Share Flipboard Email Print ThoughtCo / Chloe Giroux Geography Physical Geography Basics Political Geography Population Country Information Key Figures & Milestones Maps Urban Geography By Matt Rosenberg Geography Expert M.A., Geography, California State University - Northridge B.A., Geography, University of California - Davis Matt Rosenberg is an award-winning geographer and the author of "The Handy Geography Answer Book" and "The Geography Bee Complete Preparation Handbook." our editorial process Matt Rosenberg Updated June 24, 2019 The Amazon River in South America is an amazing and important river for the planet and therefore, you need to know about it. Here are the eight most important things you need to know about the Amazon River. 8 Amazon River Facts The Amazon River carries more water than any other river in the world. In fact, the Amazon River is responsible for about one-fifth (twenty percent) of the fresh water that flows into the world's oceans.The Amazon River is the second longest river in the world and is about 4,000 miles (6400 km) long. (In July 2007 a group of scientists reportedly determined that the Amazon River might just be the longest river in the world, taking that title from the Nile River. It will take further studies to substantiate the claim and for the Amazon River to be recognized as the longest.)The Amazon River has the largest watershed (area of land that flows into the river) and more tributaries (streams that flow into it) than any other river in the world. The Amazon River has more than 200 tributaries.Streams that begin in the Andes Mountains are the starting sources for the Amazon River.Most of the runoff of Brazil flows into the Amazon River along with runoff from four other countries: Peru, Bolivia, Colombia, and Ecuador.Due to the vast amount of water as well as sediment that are deposited where the Amazon River meets the Atlantic Ocean, the color and salinity of the Atlantic Ocean are modified for nearly 200 miles (320 km) from the delta.For much of its path, the Amazon River can be as much as one to six miles wide! During flood seasons, the Amazon River can be much, much wider; some report it is more than 20 miles wide (32 km) in certain places.The Amazon River took different routes since it began to carry water. Some scientists have determined that the Amazon River even flowed west at one time or more, into the Pacific Ocean.