ARAGUAYA, Araguay or Araguia, a river of Brazil and principal affluent of the Tocantins, rising in the Serra do Cayapó, where it is known as the Rio Grande, and flowing in a north by east direction to a junction with the Tocantins at São João do Araguaya, or São João das Duas Barras. Its upper course forms the boundary line between Goyaz and Matto Grosso. The river divides into two branches at about 13° 20′ S. lat., and unites again at 10° 30′, forming the large island of Santa Anna or Bananal. The eastern branch, called the Furo, is the one used by boats, as the main channel is obstructed by rapids. Its principal affluent is the Rio das Mortes, which rises in the Serra de São Jeronymo, near Cuyabá, Matto Grosso, and is utilized by boatmen going to Pará. Of other affluents, the Bonito, Garças, Cristallino and Tapirapé on the west, and the Pitombas, Claro, Vermelho, Tucupá and Chavante on the east, nothing definite is known as the country is still largely unexplored. The Araguaya has a course of 1080 m., considerable stretches of which are navigable for small river steamers, but as the river below Santa Anna Island is interrupted by reefs and rapids in two places—one having a fall of 85 ft. in 18 m., and the other a fall of 50 ft. in 12 m.—it affords no practicable outlet for the products of the state. It was explored in part by Henri Coudreau in 1897.

See Coudreau’s Voyage au Tocantins-Araguaya (Paris, 1897).