The Amazon is the second longest river in the world after the Nile. It flows across the continent of - South America, from the Andes mountain range to the Atlantic Ocean. The Amazon is over 4 thousand miles long and up to 2000 miles wide. Thousand of small rivers flow into the Amazon, and between them they drain half the vast continent of - South America. This area is the Amazon Basin, a huge wilderness of tropical forest and grassy plains. The Amazon begins only 100 miles from the Pacific Ocean, but it travels eastwards across the country instead of taking the quick route and flowing down the steep western slopes. Halfway along its length it reaches-Manaus, the biggest city in the Amazon region. Near - Manaus the Amazon is joined by another huge river, the Rio Negro, which has very clear water.