Over the river and through the Yellowstone woods—by snow coach.
Seasons don't matter much to Old Faithful; the geyser soars in any weather. But visit during the winter, and you'll find more steam and solitude than you'd ever get in the hubbub of summer. An early-morning February eruption might draw a crowd of one. Or two.
Snow-covered boardwalks lead past boiling pools and sputtering fumaroles that defy the freezing air. Bison hang out on bare patches of warm ground, and ducks paddle along the ice-free Firehole River. The sidewalks around the Old Faithful Snow Lodge—the only lodging in the heart of the park—are often dotted with the tracks of canines. Coyotes, not collies.
You can't drive here in the winter, but you can take a guided snow coach, a cross between a family van and a snowmobile that glides and fishtails down the road daily from either Mammoth, Wyo., or West Yellowstone, Mont. The drivers gladly stop for wildlife. Wolf packs and elk are possibilities; bison are flat-out guaranteed. (866) 439-7375, yellowstonenationalparklodges.com.