Bruneau Dunes State Park in southwestern Idaho is home to the tallest single-structured sand dune in North America, rising about 470 feet above the desert floor. The dunes formed over thousands of years and sit next to small lakes, creating one of the most surprising landscapes in the state. Visitors can hike to the crest of the big dune, try sand sliding or sandboarding, and fish or paddle on the dune lakes. The park also has a public observatory, and its dark desert skies make it an outstanding place for stargazing on clear nights. Entry is $5 per vehicle, with camping available for $15 to $50 per night. Bring plenty of water and sun protection in summer, since the dunes can get very hot.