Iriri River Iriri River The Iriri River () is a large tributary of the Xingu River in Brazil, in the state of Pará. It is long making it the 116th longest river in the world (with Krishna River, India) and the 15th longest in the Amazon basin. The headwaters are the traditional home of the Panará people. The river rises in the Nascentes da Serra do Cachimbo Biological Reserve, a strictly protected conservation unit established in 2005 in the Serra do Cachimbo. It is one of the headwaters of the Xingu River. It flows for before joining the Xingu, running through the
Tapajós-Xingu moist forests from other moist forest areas. There are urban centers at Santarém at the mouth of the Tapajós, Aveiro on the lower Tapajós and Altamira on the Iriri River. The ecoregion is crossed by the Trans-Amazonian Highway (BR-230) and the BR-163 highway from Santarém to Cuiabá. To the northwest the ecoregion adjoins the Madeira-Tapajós moist forests on the other side of the Tapajós River. To the north it adjoins the Gurupa várzea along the Amazon River. The Uatuma-Trombetas moist forests are on the opposite bank of the Amazon. To the east are the Xingu-Tocantins-Araguaia moist forests. To the south and southwest