Consequently, the Amazon river presence in the natural world isn't short of impressive – being the largest river (by discharge of water) in the world, and the second in length, with approximately 6400 meters (equivalent to 4000 miles). All this has gained it the nickname of “The River Sea”.

The Amazon River is most famously nicknamed "The Ocean River" because of its staggering scale and the fact that its mouth is so wide and powerful that it pushes fresh water miles out into the Atlantic Ocean. Early explorers were so impressed by its breadth that they felt they were sailing on a sea rather than a river. Another common nickname is "The River Sea," reflecting the same awe at its volume; it carries more water than the next seven largest rivers combined. In a more ecological sense, the entire Amazon basin is often called "The Lungs of the Planet," though this technically refers to the surrounding rainforest rather than the water itself. Locally, different sections have different names; for instance, Brazilians call the upper stretch the Solimões River until it meets the Rio Negro at the "Meeting of Waters." Regardless of the nickname, the Amazon remains the undisputed king of rivers, holding approximately 20% of the world's total river flow.