The Lesser Antilles, also known as the Caribbees, are part of the Antilles, which together with the Bahamas, the Turks and Caicos Islands, and Greater Antilles form the West Indies. The islands are a long partly volcanic island arc, most of which wrap around the eastern end of the Caribbean Sea on the western boundary with the Atlantic Ocean, and some of which lie on the southern fringe of the sea just north of South America. The Lesser Antilles more or less coincide with the outer edge of the Caribbean Plate, and many of the islands were formed as a result of subduction when one or more Atlantic plates slipped under the Caribbean Plate.