The Nairobi River and its tributaries traverse through the Nairobi Province which is the Kenyan Capital. It is the main river of the Nairobi River Basin, a complex of several parallel streams flowing eastwards. All of them join east of Nairobi and meet the Athi River, eventually flowing to the Indian ocean. These rivers are mostly narrow and highly polluted. The main stream, Nairobi River, bounds the northern city centre and is partly canalized.

The Nairobi River has several tributaries, including (from north to south):

Ruiru River Kamiti River Rui Ruaka Karura River Gitathuru River (aka Getathuru) Mathare River Nairobi River (the main channel) Kirichwa Motoine-Ngong River

Motoine River flows to the Nairobi Dam, an artificial lake meant to provide drinkable water for residents of Nairobi. Further onwards, the stream continues as Ngong River.
Nairobi's rivers suffer from contaminations by agriculture, slums and industrial areas. Some river banks are also infamous for insecurity. Proper crossings on these rivers are few and far between, resulting in a divided city.