The Niger is the third-longest river in Africa. Its catchment area includes 2,261,763 km².
Its source is located in the mountains of south Guinea, close the border to Sierra Leone. From there, it flows through Mali, Niger and Nigeria, until it flows after 4,184 km into the Gulf of Guinea. The Benue is its principal tributary.

On its way, the Niger flows in a the form of a large arc towards the northeast and forms the Massina in Mali, a vast inundation lowland with a delta that is about 40,000 km² large. The cities of Djenné and Mopti are located there. Further downstream, the Niger passes near Timbuktu where he touches the Sahara and then it flows in south-eastern direction. Afterwards, it flows through the Republic of Niger whose capital Niamey is built at its banks. Further down, the Niger forms the border to Benin and passes Nigeria. It flows into the Gulf of Guinea in form of a large delta. There, it carries about 6,000 m³/s of water on annual average.