Amazon is the largest river in the world because it contains more water than any other river on the earth — it contains about 25% of all the water (excepting sea water) that runs off the Earth’s surface. The Amazon rises high up in the Andes Mountains in Peru, flows across a length of 6,448 km from Northern Brazil to the Atlantic Ocean and on the way it is fed by about 15,000 tributaries and sub-tributaries.
The true source of Amazon was discovered in 1971 by Loren McIntyre in the snow-covered Andes of Southern Peru. The Amazon begins with snowbound lakes and brooks, and from the confluence of two major headstreams, the Maranon and Ucayali, the river is called Amazon.
The Amazon was first discovered in 1499 by Vicente Yanez Pinzon — a Spanish sea captain who was a part of Columbus’ crew on his great voyage. As Pizon was sailing out of sight off the coast, he discovered that he was voyaging through fresh water. He moved shorewards to investigate and anchored in the mouth of the vast river.
One of the most intriguing things about the Amazon is that its tributaries are distinctly of different colours. The true source of the main river is 5,240 metres above the sea-level in Peruvian Andes, and this starts off as white or dirty yellow. All the tributaries to the Amazon which run through the Andes are similar in colour as they carry heavy quantities of whitish soil in their waters. Many of its other tributaries which originate in northwest Brazil and Venezuela are apparently black in colour. In fact, these rivers are very clear and dark red in colour because they flow over ancient bare rock formations, and are relatively free of sediment but laden with iron.
Of late, Amazon has been categorized as the longest river of the world along with river Nile. A latest survey of the length of Amazon puts it at 6,750 km which exceeds the length of Nile by 80 km. But which is longer is more a matter of definition of length of a river than the simple measurement of length.