Itaituba on the bank of the Tapajós River
|- left||Juruena River, Arapiuns River|
|- right||Teles Pires, Cururu River, Das Tropas River, Crepori River, Jamanxim River|
|- location||Juruena–Teles Pires junction, Brazil|
|- location||Santarém, Pará State, Brazil|
|Length||1,200 mi (1,931 km) including Juruena River|
The Tapajós (Portuguese: Rio Tapajós) is a river in Brazil. It runs through the Amazon Rainforest and is a major tributary of the Amazon River. When combined with the Juruena River, the Tapajós is approximately 1,200 mi (1,900 km) long. For most of its length it runs through Pará State, but the upper (southern) part forms the border between Pará and Amazonas State. The source is at the Juruena–Teles Pires river junction. The Tapajós River basin accounts for 6% of the water in the Amazon Basin, making it the fifth largest in the system.
From the lower Arinos River (a tributary of Juruena) to the Maranhão Grande falls are a more or less continuous series of formidable cataracts and rapids; but from the Maranhão Grande to the mouth of Tapajós, about 188 mi (303 km), the river can be navigated by large vessels.
For its last 100 mi (160 km) it is between 4 and 9 mi (6.4 and 14 km) wide and much of it very deep. The valley of the Tapajós is bordered on both sides by bluffs. They are from 300 to 400 ft (91 to 120 m) high along the lower river; but a few miles above Santarém, they retire from the eastern side and do not approach the Amazon floodplain until some miles below Santarém.
The eastern border of Amazônia National Park is formed by the Tapajós River. From Itaituba and southwest a part of the Trans-Amazonian highway (BR-230) follows the river, while a part of BR-163 runs parallel to the river from Santarém and south.
About 325 fish species are known from the Tapajós River basin, including 65 endemics. Many of these have only been discovered within the last decade, and a conservative estimate suggests more than 500 fish species eventually will be recognized in the river basin. Some of these may be threatened by the many dams that are planned on the river.
In popular culture 
The river is the sixth title of the album Aguas da Amazonia.
- Ziesler, R., and G.D. Ardizzone (1979). Amazon System in The inland waters of Latin America. Fisheries and Aquaculture Department, Food and Agriculture Organization. ISBN 978-9250007809.
- Hales, J., and P. Petry (2013). Tapajos - Juruena. Freshwater Ecoregions of the World. Retrieved 16 February 2013.
- The Great Rivers Partnership: Tapajós River Basin. Retrieved 16 February 2013.
Further reading 
- Heinsdijk, Dammis, and Ricardo Lemos Fróes. Description of Forest-Types on "Terra Firme" between the Rio Tapajós and the Rio Xingú in the Amazon Valley. 1956.