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.

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's 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 5 1/2 -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 visitors' center before you go.