Vashon is a census-designated place (CDP) in King County, Washington, United States. It covers an island alternately called Vashon Island or Vashon-Maury Island, the largest island in Puget Sound south of Admiralty Inlet. The population was 10,624 at the 2010 census and the size is 37 square miles (96 km2), slightly larger than Manhattan. There are no bridges to connect the island with the mainland, a big factor contributing to the island's relative isolation and rural character.