Ellisville Harbor State Park is a nature preserve and public recreation area located in the village of Ellisville, Massachusetts, United States, on the western shore of Cape Cod Bay. Natural features of the coastal property include a barrier beach, sphagnum bog, salt marsh, rolling meadows, and red pine forest habitats. Scenic features include views of the South Shore coastline, small fishing boats, harbor seals seen offshore during fall and winter, and birds attracted to the park's bog as both habitat and migration stopover. The state park is managed by the Department of Conservation and Recreation.