Great Sand Dunes National Park and Preserve is situated in the San Luis Valley, Colorado. As the name suggests, the park’s most prominent feature is its sand dunes – the tallest in North America, rising to 228.6 m (750 ft) tall. The park covers an area of 179.1 km2 (69.1 sq mi) and the preserve a further 168.7 km2 (65.1 sq mi).
It is believed that the dunes began to form less than 440,000 years ago. They were created by westerly winds collecting sand particles from the flood plain and depositing them at the edge of the valley. The dunes continue to grow and change shape from day to day.
The landscape of the park is not limited to sand dunes; visitors can also enjoy the beauty and wildlife of mountains, forests, grasslands and alpine lakes.
One of the park’s most beloved features is a creek to the south of the dunes. During the spring and summer months, water runoff from the mountains create Mosca Creek. Visitors gather here as they would at any beach. The sand is a great location for picnics, sand castle building, beach sports and paddling in the sun-warmed shallow waters of the creek.
Medano Creek to the east of the dunes is also a popular spot. The waters here have an unusual feature - ocean-like waves. The waves are caused by sand constantly falling into the creek. Small dunes under the water form and break down causing surges up to a foot in height. Visitors often build sandcastles with the damp sand and skimboard in the shallow waters.
Hiking to explore the dunes is possible, although there are no marked trails, so it is recommended that hikers keep the visitor centre in sight or bring a compass. Dune sledding is a popular activity and the Park Service offers hints about the best time to sled and the most suitable equipment.