Mount Desert Island in Hancock County, Maine, is the largest island off the coast of Maine. With an area of 108 square miles (280 km2) it is the 52nd-largest island in the United States, the sixth-largest island in the contiguous United States, and the second-largest island on the Eastern Seaboard, behind Long Island and ahead of Martha's Vineyard. According to the 2010 census, the island has a year-round population of 10,615. In 2017, an estimated 3.5 million tourists visited Acadia National Park on MDI. The island is home to numerous well-known summer colonies such as Northeast Harbor and Bar Harbor.