Costa Rica (kos'tu rē'ku) [key], officially Republic of Costa Rica, republic (2005 est. pop. 4,016,000), 19,575 sq mi (50,700 sq km), Central America. It is bounded on the north by Nicaragua, on the east by the Caribbean Sea, on the southeast by Panama, and on the south and west by the Pacific Ocean. The capital and largest city is San José. In addition to the capital, other important cities are Alajuela, Heredia, Puntarenas, and Cartago.