Rock Island State Park occupies a remote island off Wisconsin’s Door Peninsula, where Green Bay meets Lake Michigan, and its limited access by ferry or private boat helps preserve a quiet, foot-travel character. Proposed in 1961 and acquired by the state in 1965 after negotiations over the Thordarson estate, the park combines natural scenery with a layered human history. Its notable features include remnants of inventor Chester H. Thordarson’s estate, such as the stone Viking boathouse and water tower, as well as Native American artifacts and the Pottawatomie Light, Wisconsin’s oldest lighthouse. The island also serves recreation, hunting, winter travel, and occasional cultural events.