Amazon river dolphin widespread river dolphins. They are present in six countries in South America: Bolivia, Brazil, Colombia, Ecuador, Peru, and Venezuela, in an area covering about . The boundaries are set by waterfalls, such as the Xingu and Tapajós rivers in Brazil, as well as very shallow water. A series of rapids and waterfalls in the Madeira River have isolated one population, recognized as the subspecies "I. g. boliviensis", in the southern part of the Amazon basin in Bolivia. They are also distributed in the basin of the Orinoco River, except the Caroni River and the upper Caura River in Venezuela. The
Xingu-Tocantins-Araguaia moist forests ecoregion rises into the Carajás Mountains, where it becomes interspersed with areas of seasonal forest and cerrado. Population centers include São Félix do Xingu on the Xingu, Porto de Moz, Oeiras do Pará and Gurupá on the Amazon, and Marabá on the Tocantins. The Marajó várzea at the mouth of the Amazon lies to the north. To the west, on the other side of the Xingu River, is the Tapajós-Xingu moist forests. To the northeast is the Tocantins/Pindare moist forests. To the southeast and south the ecoregion blends into the Mato Grosso seasonal forests ecoregion, and in some places directly