Idaho

A natural oddity created by the convergence of two prevailing winds, Bruneau Sand Dunes have been here for as long as 15,000 years. The largest stands 470 feet tall provides an impressive slide for those energetic enough to make their way to the top. The park also boasts a lake and marshland, attracting large numbers of birds and birdwatchers. Other activities open to visitors include swimming, boating and fishing; there's a 9-mile equestrian trail and a public observatory allows views of the clear night skies. ...