Rock Island State Park is a 912-acre (369 ha) Wisconsin
state park located on Rock Island, off the tip of the Door Peninsula in Lake Michigan. The only public transportation to the island is by the passenger ferry "Karfi" from Washington Island. However, there is mooring/dock space for people with their own boats, and during winter, the island is accessible via snowmobile and foot traffic. No "wheeled vehicles" (cars, all-terrain vehicles, bicycles, etc.) are allowed to be brought onto the island by visitors (although park staff use them routinely).
Attractions include the stone Viking boathouse and other structures built by inventor Chester H. Thordarson, Native American artifacts, as well as Potawatomi Lighthouse (Wisconsin's oldest lighthouse). The island is a popular destination in the fall for deer hunters and in the winter for snowmobilers from nearby Washington Island. The park has campsites available and is a destination for daytrippers.