section_path: Geography
section_name: Geography
paragraph_text: Geography
  
  Nigeria is located in western Africa on the Gulf of Guinea and has a total area of 923,768 km (356,669 sq mi), making it the world's 32nd-largest country. Its borders span 4,047 kilometres (2,515 mi), and it shares borders with Benin (773 km or 480 mi), Niger (1,497 km or 930 mi), Chad (87 km or 54 mi), and Cameroon (including the separatist Ambazonia) 1,690 km or 1,050 mi. Its coastline is at least 853 km (530 mi). Nigeria lies between latitudes 4° and 14°N, and longitudes 2° and 15°E. The highest point in Nigeria is Chappal Waddi at 2,419 m (7,936 ft). The main rivers are the Niger and the Benue, which converge and empty into the Niger Delta. This is one of the world's largest river deltas and the location of a large area of Central African mangroves.
  
  Nigeria's most expansive topographical region is that of the valleys of the Niger and Benue river valleys (which merge and form a Y-shape). To the southwest of the Niger is a "rugged" highland. To the southeast of the Benue are hills and mountains, which form the Mambilla Plateau, the highest plateau in Nigeria. This plateau extends through the border with Cameroon, where the montane land is part of the Bamenda Highlands of Cameroon.
  
  The far south is defined by its tropical rainforest climate, where annual rainfall is 1,500 to 2,000 millimetres (60 to 80 in) per year. In the southeast stands the Obudu Plateau. Coastal plains are found in both the southwest and the southeast. Mangrove swamps are found along the coast.
  
  The area near the border with Cameroon close to the coast is rich rainforest and part of the Cross-Sanaga-Bioko coastal forests ecoregion, an important centre for biodiversity. It is a habitat for the drill primate, which is found in the wild only in this area and across the border in Cameroon. The areas surrounding Calabar, Cross River State, also in this forest, are believed to contain the world's largest diversity of butterflies. The area of southern Nigeria between the Niger and the Cross Rivers has lost most of its forest because of development and harvesting by increased population and has been replaced by grassland.
  
  Everything in between the far south and the far north is savannah (insignificant tree cover, with grasses and flowers located between trees). Rainfall is more limited to between 500 and 1,500 millimetres (20 and 60 in) per year. The savannah zone's three categories are Guinean forest-savanna mosaic, Sudan savannah, and Sahel savannah. Guinean forest-savanna mosaic is plains of tall grass interrupted by trees. Sudan savannah is similar but with shorter grasses and shorter trees. Sahel savannah consists of patches of grass and sand, found in the northeast.