Nigeria is a country located in West Africa along the Gulf of Guinea. It has a long coastline and many rivers and creeks along the coast that are lined with mangrove swamps. Traveling inland, the landscape changes to tropical rainforest and then savannas and highlands in the center of the country. Nigeria has a tropical climate with two main regions - the south receives high rainfall year-round while the north has a dry season when the harmattan wind blows south from the Sahara Desert. Nigeria has a population of over 128 million people from several hundred ethnic groups and it is Africa's most populous country.