Manaus : Meeting of the Waters : a mix between the Rio Negro (dark cool water on the right hand side, ph 7) and the yellow water of the Rio Solimoes (yellow warm Water on the Left Hand Side, ph = 7). The two Rivers don't mix because of two different Velocity, Density, Temperature and acidity (pH). Nearby Manaus 20 km. Amazonia, Manaus, Amazonas State. Brazil.