The Great Sand Dunes in Colorado provide a picture of serenity. Nestled in a spot where the Sangre de Cristo Mountains buckle inward, the dunes within the borders of Great Sand Dunes National Park have been building and sifting for eons � the result of the San Luis Valley's unique wind patterns. A sandbox of epic proportions, the entire dune field encompasses 30 square miles and the tallest dune towers 750 feet high. The kid in every visitor loves to sled down the sand year-round and plunge into the soft-sand tracks of those who climbed ahead of them.