Sierra Leone, officially the Republic of Sierra Leone, is a country on the southwest coast of West Africa. It shares its southeastern border with Liberia, and the northern half of the nation is surrounded by Guinea. Covering a total area of 71,740 km2, Sierra Leone has a tropical climate, with diverse environments ranging from savanna to rainforests. The country has a population of 7,092,113 as of the 2015 census. Freetown is the capital and largest city.