Martha's Vineyard, often simply called the Vineyard, is an island in the U.S. state of Massachusetts, lying just south of Cape Cod. It is known for being a popular, affluent summer colony, and includes the smaller peninsula Chappaquiddick Island. It is the 58th largest island in the U.S., with a land area of about 96 square miles (250 km2), and the third-largest on the East Coast, after Long Island and Mount Desert Island. Martha's Vineyard constitutes the bulk of Dukes County, Massachusetts, which also includes the Elizabeth Islands and the island of Nomans Land.