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, an incredible 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 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.