Great Sand Dunes National Park, located in the state of Colorado in the United States, encompasses an area of 340 square kilometers (130 square miles, or 85,000 acres) of magnificent sand dunes. The 12,000 year old sand dunes include the tallest dunes in North America, rising 230 meters (750 feet) above the valley floor. The park contains other landscape features found in the high desert, such as alpine lakes, tundra, forests, grasslands, and wetlands, all of which provide habitats for many kinds of wildlife. Visitors to the park can enjoy hiking over the dunes, though it is wise to either keep the visitor center in sight, or bring a compass, as there are no marked trails on the ever-changing dunes. The closest town with accommodation is Alamosa, 30 miles southwest of the park. There is also tent camping available within the park. The nearest international airport is located in Denver, the capital of Colorado, which is a 4 1/2 hour drive from the park.