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The greatest of rivers begins with a small trickle from a glacier high in the Andes, 150 kilometers from the Pacific Ocean. This thin stream feeds into Lake Ninococha, which itself pours out as the Maranon River. After coursing through 1000 kilometers of the Andes, the Maranon descends into the vast rain forest of equatorial South America. Brazil covers most of this region. As it continues on, traveling 4000 kilometers to the east, it is joined by more than 1000 other tributaries to form the Amazon, which is regarded as being the mightiest of all rivers. Into the Atlantic Ocean it flows, carrying 100,000 tons of silt each hour and delivering enough water to fill 60 Olympic swimming pools each second.