Which is the longest river in the world?

For many years, every textbook said the Nile. The Nile flows north through eleven African countries into the Mediterranean Sea, and it is about 6,650 kilometres long.

Then scientists measured the Amazon in South America again, including a longer source high in the mountains of Peru. Some now say the Amazon is slightly longer, at around 6,900 kilometres. Others disagree about where a river really begins. So the honest answer is: it depends who measures.

One fact is not argued: the Amazon carries far more water than any other river — about one-fifth of all the river water flowing into the world’s oceans.

India’s longest river is the Ganga, about 2,500 kilometres. Kerala’s longest is the Periyar, 244 kilometres, which gives Kochi its drinking water and electricity.