Amazon, a river of South America, the largest in the world. Its head waters are fed by the perpetual snows of the Andes, a few hundred miles from the Pacific Ocean. It flows in a general north-northeasterly direction, receiving enormous tributaries, and finally discharges its waters into the Atlantic under the equator in a mighty flood 150 miles wide. The Amazon is 4,000 miles long. It has a hundred navigable tributaries. Seventeen of the largest are from 1,000 to 2,300 miles in length. The entire Amazon system affords over 50,000 miles of navigable waterways. In the lower 750 miles of its course, from the mouth of the Rio Negro to the Atlantic, the main river is nowhere less than 180 feet in depth. Other rivers are longer, but of all rivers in the world none equals the Amazon in volume. Roughly stated the Amazon carries to the sea not each hour, but each minute, a volume of water represented by eighty acres fifty feet deep. Its basin, also the largest in the world, covers 1,900,000, some authorities say 2,500,000, square miles, or nearly a third of all South America. From the headwaters of the Amazon, the Indian in his canoe may pass north by connecting streams into the Orinoco or south to the Rio de la Plata. The entire central and eastern part of the Amazon Valley is occupied by dense forests. Surrounding the forest region toward the west, and lying between its tributaries, are vast savannas or treeless grassy tracts. The waters are thronged with turtles and crocodiles, water fowl, tapirs, and anacondas, and teem with fishes. Agassiz described 1,163 species of the latter. The forests, impassable jungles of trees and tropical vines, are inhabited by monkeys, parrots, sloths, tapirs, boa constrictors, and pumas. Along the rivers Indians live in villages and barter with white traders marketing dyewoods, rubber, and Brazil nuts. Para, near the mouth, is the chief port of the Amazon. Perhaps half a hundred steamers ply between Para and up river landings. They bring down forest products, including lumber and dyewoods, and carry up groceries, tools, and clothing. The basin of the Amazon comprises the largest tract of fertile unimproved land in the world. Its only rival in this respect is the valley of the Congo. See BRAZIL-NUTS; RUBBER; BOA CONSTRICTOR; TAPIR; WALLACE; SOUTH AMERICA.