Most of Yellowstone is closed to auto traffic in winter, but the part that is open to cars offers some of the richest wildlife viewing opportunities in the park. It runs from the park's northern entrance at Gardiner to the snowbound community of Cooke City, Mont., at the northeast entrance (the road beyond Cooke City is closed in winter).

En route, it passes through the Lamar Valley, which some have called America's Serengeti. This is where most of the park's wolf watchers hang out.

But even areas closed to auto traffic remain open to visitors, via snowmobile or snowcoach. Visitors can travel by snowcoach to Old Faithful and ski the circuit around the Upper Geyser Basin, the largest geyser concentration in the world. After skiing, visit the Old Faithful Snow Lodge, a modern hotel that invites visitors to curl up in comfy lounging chairs in front of lobby fireplaces. (Yellowstone's winter season officially began Dec. 15, but due to a sparse snowpack, snowmobiles were not being allowed in right away. Check with the park for current conditions.)

Those staying in gateway communities can also take snowcoaches into the park on day trips. Cross-country skiers can access scheduled ski drops and pickups for specific trails from in-park hotels.

And for those staying near the north entrance, winter is the best time to try that special Yellowstone experience called hot-potting.

As you drive the five miles from Gardiner to Mammoth Hot Springs, you will cross the Gardner River. You may notice a big parking lot to your left — seemingly serving nothing. It's not marked, but this is the best opportunity in Yellowstone to take a dip in a wild hot springs without having to hike for 20 miles first.

Park rules require that you walk upstream about a half-mile from the parking area to where the footpath reaches the river. Here waters from the Boiling River hot spring mix in pools with cold water from the Gardner River. (Note that hot-potting is allowed during daylight hours only.)

You won't be alone. And take care in how you dress — there are no changing rooms (but bathing suits are required), and you'll have that hike back through the snow and wind after your dip. But the experience of soaking in steaming hot water in a river during a snowstorm is one you will never forget.