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 , 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.