Close to the northern border of New Mexico in the Tularosa Basin, White Sands National Monument covers a swath of land with dusty fine and brilliantly white gypsum sand. It's rare because normally gypsum would be immediately carried away by rains, but the Tularosa Basin is enclosed with no outlet, and so the sand collects into blinding dunes.
Since the sand is so white, it's surprisingly cool to the touch even during hot summer days, and the National Park station hands out large discs so visitors can sled down the dunes. It very much seems like an extensive playground, though the reflected light is hard on the eyes after a short while.