Saint Lucia Listen/seɪnt ˈluːʃə/ is a sovereign island country in the eastern Caribbean Sea on the boundary with the Atlantic Ocean. Part of the Lesser Antilles, it is located north/northeast of the island of Saint Vincent, northwest of Barbados and south of Martinique. It covers a land area of 617 km (238.23 sq mi) and has a population of 174,000 (2010). Its capital is Castries.