Located in northern Alaska near Kotzebue, this unique park is only accessible by boat, plane or foot. If you are up for an ultimate adventure, you could bring along your packable boat and have a pilot drop you at a remote location to float through the park. (Please, prepare yourself very well for an excursion like this.) While this park is open year-round, a visit between May and September is advisable for the best experience. You might be surprised to find out that you can explore giant sand dunes at this location as well (Great Kobuk Sand Dunes)…but leave the bikinis at home.