"Isle Royale National Park is one of the country’s least-visited national parks. The park can only be reached by ferry or seaplane and is open from April 15 to Nov. 1. It spans 132,018 acres and can only be explored on foot. Kayaking is popular, and visitors can stay in one-room cabins at Windigo Camper Cabins or at Rock Harbor Lodge." - Travel + Leisure Editors