Downriver from Manaus, the 'black' (actually reddish-brown) water of the Rio Negro meets the 'white' (light brown) water of the Rio Solimões, but owing to differences in speed, density and temperature, the waters don't immediately mix. Instead, they flow side by side for several kilometers, an occurrence known as the Encontro das Águas.
The phenomenon, which occurs in several places along the river, was the inspiration for the wavy black-and-white tile work in front of the Opera House, and borrowed again for Rio de Janeiro's famous beach promenade. Boat trips to see the meeting of the waters are typically combined with a highly packaged tour of Parque Ecológico Janauary (Janauary Ecological Park; M0745), where you'll cut the same rubber tree, admire the same water lilies, and look at the same captured animals as thousands before you. Then lunch, then shopping, then home.
