<P> At some points the river divides into anabranches, or multiple channels, often very long, with inland and lateral channels, all connected by a complicated system of natural canals, cutting the low, flat igapó lands, which are never more than 5 metres (16 ft) above low river, into many islands . </P> <P> From the town of Canaria at the great bend of the Amazon to the Negro, vast areas of land are submerged at high water, above which only the upper part of the trees of the sombre forests appear . Near the mouth of the Rio Negro to Serpa, nearly opposite the river Madeira, the banks of the Amazon are low, until approaching Manaus, they rise to become rolling hills . </P> <P> The Lower Amazon begins where the darkly coloured waters of the Rio Negro meet the sandy coloured Rio Solimões, and for over 6 km (4 mi) these waters run side by side without mixing . At Óbidos, a bluff 17 m (56 ft) above the river is backed by low hills . The lower Amazon seems to have once been a gulf of the Atlantic Ocean, the waters of which washed the cliffs near Óbidos . </P> <P> Only about ten percent of the Amazon's water enters downstream of Óbidos, very little of which is from the northern slope of the valley . The drainage area of the Amazon basin above Óbidos city is about 5,000,000 square kilometres (1,900,000 sq mi), and, below, only about 1,000,000 square kilometres (390,000 sq mi) (around 20%), exclusive of the 1,400,000 square kilometres (540,000 sq mi) of the Tocantins basin . The Tocantins River enters the southern portion of the Amazon delta . </P>

Where did the amazon river start and end