The Niger River (/ˈnaɪdʒər/ NY-jər; French: (le) fleuve Niger, pronounced: [(lə) flœv niʒɛʁ]) is the principal river of western Africa, extending about 4,180 km (2,600 mi). Its drainage basin is 2,117,700 km² (817,600 sq mi) in area. Its source is in the Guinea Highlands in southeastern Guinea. It runs in a crescent through Mali, Niger, on the border with Benin and then through Nigeria, discharging through a massive delta, known as the Niger Delta or the Oil Rivers, into the Gulf of Guinea in the Atlantic Ocean. The Niger is the third-longest river in Africa, exceeded only by the Nile and the Congo River (also known as the Zaïre River).