Great Sand Dunes National Park and Preserve ( https://www.nps.gov/grsa/index.htm) has the highest sand dunes in North America. Nestled against the 13,000 foot peaks of the San Juan Mountains in the San Luis Valley south of Denver, the dune field is at 8,200 feet and the highest dune is 750 feet. Between the mountains and the dunes, the Medano River runs in the spring as the snow is melting. This is a very shallow river that "pulses" - see web site.

The weather is often extreme with summers being very hot and winters very cold. On my last trip in May, it snowed the night before we arrived so the dunes were wet and looked much different than in my earlier trip during the summer. And of course, in the spring, you get beautiful snow-covered peaks on the surrounding mountains. You will notice a significant difference in the photos shown under Summer and Spring.

There is one main trail to the top of the dunes but mostly people just wander wherever they want. There are other hikes in the park that you may want to check out. They have a campground with many of the sites having views of the dunes.