Yes, you need a permit to camp in the backcountry of Great Sand Dunes National Park. Backcountry camping permits are required for overnight stays in the dunefield outside of the day-use area. You can obtain a permit at the park's visitor center during their operating hours. Keep in mind that backcountry permits are not required for camping in the designated Pinon Flats Campground, which operates on a first-come, first-served basis or through reservations during the peak season (May through September).