The muddy river that stretches west from Manaus  all the way to Brazil ’s border with Peru  and Colombia is known as the Rio Solimões. Although it is actually more of a café-au-lait color, the Rio Solimões is known as a “white” river due to the fact that its waters are laden with a high concentration of rich soil.
As a result, during the wet season when the river floods the surrounding land, it leaves highly fertile silt deposits that encourage plant, animal, and insect life. The ramifications for ecotourists are twofold: While you’ll tend to see more wildlife along the Rio Solimões than along the Rio Negro, you’ll also have to fend off more mosquitos.
Traveling upstream by boat along the Rio Solimões, there are several areas that offer stunning expanses of prime rainforest with the possibility of viewing wildlife. Only a half-day journey from Manaus  is the area surrounding Lago Mamori, where you can glimpse lots of birds, caimans and pink river dolphins and the piranha fishing is great. Further along, and more remote, is the Lago Juma.