The Niger River is the principal river of West Africa, flowing 4,180 kilometers. It has an unusual boomerang shape, starting just 240 kilometers from the Atlantic Ocean but flowing inland away from the sea into the Sahara Desert before turning sharply southeast to empty into the Gulf of Guinea in Nigeria. This strange course baffled European explorers for centuries. The river is vital for the Sahel region, providing water for irrigation and transport in landlocked countries like Mali and Niger. The Inner Niger Delta is a massive area of lakes and floodplains in Mali that supports millions of people and migratory birds. The river's mouth, the Niger Delta, is a vast wetland famous for its mangrove forests and significant oil and gas deposits, which are the backbone of Nigeria's economy.