In Manaus, the capital of Amazônia, the two biggest rivers of the Amazon meet and flow side-by-side over distance of six kilometres.
The Solimões River is the brighter half, its colouring owed to the rich sediment that runs down from the 1600 km far Andes Mountains.
The darker side is the Rio Negro. Its darker colour is owed from leaf and plant matter that has decayed and dissolved in the water. Even it might look dark and murky the Rio Negro is considered one of the cleanest natural waters in the world.
And why they flow side-by-side? This natural phenomon occurs due to differences in temperature, speed and water density between the two. The Solimões is faster, cooler and denser, its waters flowing up to 6 km/h at 22 degrees Celsius, and the warmer, slower waters of the Rio Negro flow at a more leisurely 2 km/h, and maintain a temperature of around 28 degrees Celsius.
