A very uncommon fisical phenomenon in the Amazon forest, the Meeting of Waters occurs at the confluence of Rio Negro, a river with dark (almost black coloured) water, and the sandy-coloured Amazon River or Rio Solimões, as it is known the upper section of the Amazon in Brazil. For 3.7 mi the river's waters run side by side without mixing. It is one of the main tourist attractions of Manaus, Brazil.
This phenomenon is due to the differences in temperature, speed and water density of the two rivers. The Rio Negro flows at near 1.2 mi per hour at a temperature of 72°F, while the Rio Solimões flows 4 mi per hour a temperature of 83°F.
In the background, the Manaus City.