Allyn is an unincorporate community in Mason County, Washington, United States. It is part of Allyn-Grapeview, a census-designated place that also includes the community of Grapeview. Allyn is located on the western shore of North Bay region of the Case Inlet of the Puget Sound.The area's main road and thoroughfare is State Route 3. Lakeland Village development, a residential and recreational corporation begun in the late 1960's, has grown over the years into a major community and today includes over 800 homes, a 27 hole golf course, a large club house for resident and public use, and a restaurant.