Xingu River, Portuguese Rio Xingu, river in Mato Grosso and Pará states, Brazil. The river rises on the Planalto (plateau) do Mato Grosso, in the drainage basin framed by the Serra do Roncador and the Serra Formosa mountain ranges. Formed by several headstreams, principally the Curiseu, Batovi, and Romuro rivers, the Xingu meanders generally northward for approximately 1,300 mi (2,100 km), emptying into the Amazon River just south of the Ilha (island) Grande de Gurupá. South of Altamira it receives its main tributary, the Iriri (800 mi long).
Although the Xingu’s lower course is wide (2 1/2 mi) at its mouth and the channel is deep, the river is navigable only from its mouth to Sousel and Vitória, 125 mi south. Its upper course is marked by innumerable rapids. The Xingu–Araguaia Hydroelectric Project was built along the river during the late 1970s. The Xingu was first explored in 1884–87 by the German ethnologist and explorer Karl von den Steinen. In the 1950s Xingu National Park was designated as a preserve for Brazil’s Indians, including the Tchikao, who were threatened by extinction.