Hwy. 150, Mosca, Colorado
The “Great” in the name of this fascinating natural phenomenon is more than appropriate. Not only are these ever-changing dunes ranked as the tallest in North America, but the dune field stretches over 30 square miles of high mountain-valley floor. The vast expanse of sand was formed over thousands of years as sand blew off a prehistoric lake bed on the valley floor and piled up against the Sangre de Cristo mountains.
The park also includes six peaks more than 13,000 feet high, alpine tundra, forests, grasslands, and wetlands. Most popular is the natural mountain beach created by Medano Creek, which flows across the sand in waves in spring and early summer and attracts many swimmers.
Not surprisingly, this unusual park appeals to sand skiers as well as to hikers, backpackers, and campers, who stay in a campground in an area of junipers and pines at the dunes’ edge. Some visitors venture onto the dunes at night with flashlights in hopes of spotting kangaroo rats and giant sand-treader camel crickets that manage to survive in this arid environment.
The best weather is generally spring and fall. In summer, even though the air temperature is moderate, the sand can get uncomfortably hot.
Park and campground open year-round.