The Rio Purus is one of the Amazon basin's major tributaries, stretching approximately 3,211 kilometers (1,995 miles) from its headwaters in the Ucayali department of Peru through the Brazilian states of Acre and Amazonas before joining the Solimões River upstream from Manaus. The river is widely recognized as one of the world's most meandering streams — the straight-line distance from its source to its mouth is less than half the total length of its meanders. At its mouth, the river reaches approximately 1,200 meters (3,900 feet) in width and divides into numerous branches across from the Ananás e Consciência Islands.

The defining geographical character of the Purus in Amazonas is its vast, half-submerged floodplain studded with thousands of lakes, many of which are navigable. The river flows sluggishly through this low-lying, lake-flooded landscape, functioning essentially as a large drainage channel for the surrounding wetlands. The middle and lower reaches include extensive blackwater sub-basins. Water levels fluctuate dramatically between seasons, with the rainy season running roughly from December through April. During high water, river levels can rise by as much as 10 meters compared to low-water periods, dramatically altering the landscape and travel conditions. Floating villages along the river are built on logs specifically to rise and fall with these seasonal changes.

The river supports regular passenger boat traffic, and small communities are scattered along its banks. Paddlers traveling through the region may encounter passenger and cargo vessels operating along the river. The surrounding forests are home to flooded forest ecosystems, and the floodplains are subject to logging and some agricultural clearing, particularly downstream of the Acre-Amazonas border. The middle and lower Purus Basin in Amazonas state includes relatively large protected areas, with conservation efforts actively managed in this stretch.

Given the scale of seasonal flooding and the remoteness of the river corridor, paddlers should be prepared for significant logistical challenges. Communities along the route are accessible primarily by boat, and local passenger vessels regularly stop at riverside settlements. The river's extreme meandering nature means distances traveled on water are substantially greater than straight-line measurements would suggest.