Sierra Leone (/sɪˈɛərə lɪˈoʊni, -lɪˈoʊn/), officially the Republic of Sierra Leone, is a country in West Africa. It is bordered by Guinea on the north, Liberia in the south-east, and the Atlantic Ocean in the south-west. Sierra Leone has a tropical climate, with a diverse environment ranging from savannah to rainforests. Sierra Leone has a total area of 71,740 km2 (27,699 sq mi) and a population of 7,075,641 (based on 2015 national census). Freetown is the capital, largest city and its economic and political centre.