The Cordillera Septentrional is a mountain range that runs parallel to the north coast of the Dominican Republic, with extensions to the northwest, the Tortuga island, and to the southeast, with the lowlands of the Samaná Peninsula where it becomes the Sierra de Samaná. Its highest mountain is Diego de Ocampo, close to Santiago de los Caballeros, with 1,250 metres (4,100 ft). There are several small plains between this range and the Atlantic Ocean.