What other national park boasts an assortment of some 10,000 thermal features, including more than 300 geysers? Even when the rest of North America was still largely wilderness, Yellowstone was unique. Its collection of geothermal features is richer and more concentrated than any other in the world, with mud pots, geysers, and hot springs of all colors and sizes. Plus, there's a waterfall that's twice as tall as Niagara Falls and a canyon deep and colorful enough to be called "grand." Sure, other parks have great hiking trails and beautiful geologic formations -- Grand Teton is pretty spectacular in its own right, as is Yosemite -- but a sizable percentage of the geology in Yellowstone is reachable by visitors in average physical shape.
Ever focus your camera lens on an untamed grizzly bear, or a bald eagle? What about a wolf? Thousands of visitors have these experiences here every year. Protected from development by the national park and surrounding forests, Yellowstone is home to herds of bison and elk, packs of grizzly bears, flocks of trumpeter swans, schools of Yellowstone cutthroat trout, and subtler beauties such as wildflowers and hummingbirds.
And the park doesn't appeal solely to the visual senses; you'll smell it, too. By one biologist's estimate, Yellowstone has more than 1,100 species of native plants. When wildflowers cover the meadows in spring, their fragrances are overpowering. The mud pots and fumaroles have their own set of odors, although many are less pleasing than that of a wild lily.
Grand Loop Road, the 154-mile, figure-eight road looping through the heart of the park, connects most of the major and minor attractions, and you’re bound to spend some time cruising it. But stop frequently and get out of the car: Exploring the park’s highlights and, even better, getting out into the backcountry on a hiking trail will enrich your trip by leaps and bounds.
You could visit Yellowstone for a single day—and if that’s your only option, by all means, take it—but you need a minimum of 3 days to really get a feel for the place. A week or more is even better. Hit up the must-sees, such as Old Faithful, Grand Canyon of the Yellowstone, Mammoth terraces, Lamar Valley, and Yellowstone Lake, but also to check out some of the lesser-known but still incredible destinations. Attend a ranger-led program or sign up for a class with Yellowstone Forever for an in-depth experience. Consider spending a night under the stars, either in a drive-in park campground or deep in the backcountry. The farther you go from the road, the more solitude you’ll enjoy, and the more Yellowstone’s wild heart will be revealed to you.
Yellowstone closes in fall and then reopens as a winter destination come December, when cross-country skiing, snowshoeing, and snowmobiling are the prime pursuits. There's no cozier place than the lobby of the Old Faithful Snow Lodge, the only hotel in the park's interior that stays open during Yellowstone's long, cold, and snowy winter season. I highly recommend a visit when snow covers the ground. You often have the park to yourself, but dress appropriately (read: no less than three layers) and be ready to incur an extra expense in the form of snowcoach fare.
Watch Your Step! -- In thermal areas, the ground might be only a thin crust above boiling hot springs, and there's no way to guess where a safe path is. New hazards can bubble up overnight, and pools are acidic enough to burn through boots; so stay in designated walking areas.