Gateway City: Alamosa
Nearest Airport: Colorado Springs Municipal Airport (COS)
Size: 84,670 acres
Date Founded: 2004
Annual Visitation: 258,660
Busiest Month: July (60,734)
Least-Crowded Month: January (1,328)
Fees: Adult: $3
 
The enormous sandbox at the Great Sand Dunes National Preserve makes you feel, very simply, like a kid again. People of all ages run up these 700-foot-high dunes just to roll down, laughing while their shorts fill up with sand.

The dunes make for a dramatic setting on the plains of south-central Colorado, right at the foot of the Sangre de Cristo range. From the top you can see mountains on one side, while on the other, the dunes seem to stretch forever. Continue into the dunes and it's easy to convince yourself that you're in the Sahara.

It is unclear when the dunes started to form, as there is currently no accurate process to date sand. Geologists speculate that dunes probably started to form when the swollen Rio Grande spread sand across the San Luis Valley. Heavy winds carried—and still carry—the sand toward the Sangre de Cristo Mountains and dropped it off as the winds lost steam. Yet while heavy winds move the sand around quite a bit (you don't want to get caught in a sandstorm), moisture acts as a stabilizer, maintaining the height and even the contours of the dunes. Come back in ten years and they're likely to look much the same.

The dunes themselves are not a haven for tons of flora or fauna, but you will find some 20 species of plants (pinyon pine, juniper) and several more of animals (rabbits, mule deer) and birds (like the green-tailed towhee). However, Congress expanded the preserve in 2001, adding several habitats from the surrounding area. The topography of the preserve ranges from mountain tundra and pine forest to wetlands and desert, sheltering many endemic species.

Pinyon Flats campground is open year-round, and has 88 campsites available on a first-come, first-served basis. Group sites for groups of ten or more are available by reservation. Fire grates, picnic tables, flush toilets, and drinking water are available.

Play In The Sand 
Obviously. The sand is staring you in the face wherever you are. And unlike the delicate dunes of some shorelines, these hearty mounds can stand all the foot punishment you can give. It's not easy walking. Ever try climbing a beach? That's what trekking to the top of 'em feels like. The view is worth the effort, as is the fun when coming down. People run down, roll down, and ski down, even in summertime. If you fall, the mush makes for a soft landing. Just keep one eye on the weather: High winds can kick in at any time. And in winter, be prepared for snowfall.

Walk The Dunes 
While there are no hiking trails through the dunes themselves, there are trails inside the park for all levels of hikers. The Montville Nature Trail is a half-mile loop circling the lower portion of Mosca Canyon that serves up great views of the dunes. The seven-mile Mosca Pass Trail intersects the Montville Nature Trail and is a bit more strenuous, climbing almost 1,500 feet in elevation (the reward, of course, is better views). If you're looking to do some backcountry camping, hit the five-mile Little Medano Creek Trail, which heads out to where the dunes meet the mountains. There are seven backcountry sites out here; just be sure to pick up a free backcountry permit from the visitor center before you go.

Drive Medano Pass 
Don't bring the station wagon back here. The Medano Pass Primitive Road is strictly for off-roading. In fact, only high-clearance four-wheel drives and licensed motorcycles are even allowed. The entire road is about 19 miles long and passes out of the preserve. Within its boundaries, however, the road runs along the dunes and crosses Medano Creek, getting you into parts of the monument that are not easily accessible. Know the rules of off-roading—they definitely apply here. For example, since the road is soft, deep sand, you should let some air out of your tires. Also, springtime can mean high water, making for tricky creek crossings.