This 1,650-acre park is only accessible by private boat or the free park ferry. Throughout the grounds, there's evidence of Native American habitation dating back thousands of years, including a shell mound along the 3-mile hiking loop. You can walk the trails or rent a bicycle, kayak or canoe for a fee. If you want someone else to do the driving, there are several fee-based river tours in the area. A playground for the little ones, plenty of picnic tables for lunch and barbecue add to the charm. The visitor's center and museum offer a glimpse into the island's history, and a small store has various sundries. Rustic cabins are also available.