The Meeting of Waters is the confluence between the Rio Negro, a river with dark (almost black coloured) water, and the sandy-coloured Amazon River

Amazon River

The Amazon of South America is the second longest river in the world and by far the largest by waterflow with an average discharge greater than the next seven largest rivers combined...

 or Rio Solimões, as it is known the upper section of the Amazon

Amazon River

The Amazon of South America is the second longest river in the world and by far the largest by waterflow with an average discharge greater than the next seven largest rivers combined...

 in Brazil

Brazil

Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

. For 6 km (3.7 mi) the river's waters run side by side without mixing. It is one of the main tourist attractions of Manaus

Manaus

Manaus is a city in Brazil, the capital of the state of Amazonas. It is situated at the confluence of the Negro and Solimões rivers. It is the most populous city of Amazonas, according to the statistics of Brazilian Institute of Geography and Statistics, and is a popular ecotourist destination....

, Brazil.

This phenomenon is due to the differences in temperature, speed and water density of the two rivers. The Rio Negro flows at near 2 km per hour at a temperature of 28°C, while the Rio Solimões flows between 4 to 6 km per hour a temperature of 22°C.