The coastline of Nigeria is 800 km long, bounded to its immediate north by coastal sand beaches, made up of open, white, sandy surfaces for an average width of between three to five km. This coastal stretch is cut into western and eastern portions by the delta of the River Niger, which is 150 km wide, stretching inland to over 50 km. The delta is dissected by a network of river distributaries.
Behind these sandy beaches is a belt of mangrove swamps which, in some places, is about 100 km wide. Beyond this belt is a zone of tropical forests. Further inland, the land rises to an undulating plateau and series of hills of general elevation. Breaking these east to west hills are the Niger and Benue troughs. The elevation around the Jos Plateau is about 2 km, resulting in low temperatures, similar to the temperature climate in Europe and parts of North America. The vegetation on the northern plateau is typically grassland in nature, allowing for a broad view of extensive landscapes.
Nigeria is entirely between the equator and the Tropic of Cancer. Nigeria's climate varies from tropical (at the coastal areas) to subtropical (in the northern areas). There are two main seasons - the dry season, lasting from November to March; and the rainy season, from April to October. Temperatures at the coast rarely rise about 32�C (89.6ºF), although humidity can be as high as 95%. The climate further north is drier, with temperatures ranging from 36ºC (96.8ºF) to 12ºC (53.6ºF). During the rainy season, tropical thunderstorms are a periodic occurance, especially in the coastal areas, but it is generally a period of cooler temperatures and more agreeable climate.
The most important river in Nigeria is the River Niger, which takes its source from the hills of Futa Jalon. It is about 4170 km long, but only 1/3 of this length is within Nigeria. It enters Nigeria from the west and flows south-easterly until it joins the River Benue, almost at the center of Nigeria.
The Benue is the second most important river in Nigeria. It takes its source in the northern section of the central hills of the Cameroon Republic, and enters into Nigeria from the east. It flows south-west to join the Niger at Lokoja. Other important rivers in Nigeria are Sokoto, Yobe, Hadejia, and Kaduna in the north and Ogun, Osun, Owena, Osse, Anambra, and Cross River, in the south.
The mangrove forests of the south are criss-crossed by a network of lagoons, mostly in an east-west direction.