The document summarizes information about the Great Sand Dunes National Park. It describes the park as having the largest sand dunes in the United States, covering over 84,000 acres, with dunes rising to nearly 700 feet high. The document notes that the dunes are considered one of the most haunted hiking places and that visitors have reported seeing and feeling ghosts. It provides details on the formation of the dunes over 440,000 years ago and lists activities for visitors such as sliding down dunes, hiking, camping, and seeing the wildlife.