The Rio Araguaia originates in the Serra dos Caiapós within the Brazilian Highlands of eastern Mato Grosso state, at elevations around 800 meters near the town of Alto Araguaia. From there it flows north-northeast for approximately 2,627 kilometers, forming the border between Mato Grosso and Goiás before continuing through Tocantins and Pará. The river drains a vast portion of the Cerrado savanna and transitional forest zones, encompassing elements of the Cerrado, Pantanal, and Amazônia biomes. Its Tupi name, "rio das araras," reflects the extraordinary birdlife found along its banks.

The river is long and relatively shallow, lacking a firm riverbed, and its course includes many lakes, broad white-sand beaches, and oxbow formations. The major western arm is interrupted by numerous falls and rapids, making navigation challenging in places, while the smaller eastern channel is more navigable by small boats. During the wet season the river floods well beyond its banks, inundating surrounding forest. The dry season, running roughly from June to October, is generally considered the better period for paddling and wildlife observation, as seasonal beaches emerge and water levels stabilize.

A notable paddling route in the Mato Grosso section runs from Barra do Garças downstream toward Araguaiana, a stretch that has been used for multi-day kayak expeditions. This segment offers access to the river's characteristic wide, sandy beaches and open floodplain scenery. Barra do Garças serves as a practical base for trips in this part of the river.

Wildlife along the river is diverse and visible, including capybaras, caimans, giant otters, and black caimans. The birdlife is particularly rich, with herons, bem-te-vis, sabiás, azulões, uirapurus, and various migratory species present. The river supports nearly 300 species of fish, making it a significant destination for fishing tourism as well.

Paddlers should be aware that the river's upper and middle course presents falls and rapids that interrupt navigation, and seasonal flooding can dramatically alter conditions. The combination of remote stretches, variable water levels, and wildlife including large caimans warrants careful trip planning and appropriate safety preparation.