The Meeting of the Waters
Rio Negro at Sunset © P199
Where the dark waters of the Rio Negro join the lighter, muddy waters of the Rio Solimoes, a natural phenomenon results: the separate shades of water run side by side for a length of more than four miles (6km) without mixing. The separation is apparently caused by the difference in temperature, density and flow of the waters from each river: Rio Negro travels at about a mile (2km) per hour with a temperature of 72ºF (22ºC), while Rio Solimoes flows at between two and four miles (4-6km) per hour with a temperature of 82ºF (28ºC). This phenomenon has become a major tourist attraction in Brazil, best accessed by taking an hour's journey by boat from the floating docks in Manaus to see the dramatically divided waters.