The Juruá–Purus moist forests ecoregion is in the state of Amazonas in northwest Brazil to the south of the Solimões, or upper Amazon River.

The terrain consists of flat, forest-covered plains cut by large, meandering rivers with many oxbow lakes and thousands of smaller watercourses, all of which flood each year.

The sediments of the low Amazon basin were formed during the late Tertiary period, and are relatively young and easily eroded.

A few giant trees have trunks up to 240 centimetres (94 in) wide such as Cariniana decandra, Osteophloem platyspermum, Piptadenia suaveolens, genus Brosimum, Eschweilera blanchetiana and Sclerobium paraense.

[3] As with other parts of the Amazon rainforest the most important families of trees are Fabaceae, Sapotaceae, Lecythidaceae, Moraceae, Chrysobalanaceae, Lauraceae and Myristicaceae.

[3] Large mammals include silky anteater (Cyclopes didactylus), southern tamandua (Tamandua tetradactyla), giant anteater (Myrmecophaga tridactyla), brown-throated sloth (Bradypus variegatus), jaguar (Panthera onca), cougar (Puma concolor), red brocket (Mazama americana), gray brocket (Mazama gouazoubira) and South American tapir (Tapirus terrestris).

[3] Species local to the Southwestern Amazon Moist Forests include the short-eared dog (Atelocynus microtis), Linnaeus's two-toed sloth (Choloepus didactylus), pygmy marmoset (Cebuella pygmaea), brown-mantled tamarin (Saguinus fuscicollis) and Goeldi's marmoset (Callimico goeldii).

[5] Endangered mammals include Peruvian spider monkey (Ateles chamek) and giant otter (Pteronura brasiliensis).

Petrobras has undertaken oil and natural gas exploration in the region for many years, creating deforested patches.

Urban centers and small farming settlements along the rivers are surrounded by land cleared for houses, agriculture and livestock pasturage.

A planned extension of the Trans-Amazonian Highway from Lábrea on the Purus River to Tabatinga on border between Peru, Brazil and Colombia would cause widespread habitat destruction.