Yellowstone is an anomaly among national parks. Established as the country’s first in 1872, the park nurtures almost half the world’s geysers and the largest number of wildlife including moose, black bears, and bison.

Stretching about 3,457 miles along the state’s northwest, the Yellowstone spills over into Montana and Idaho. Since the release of wolves into the park, Yellowstone’s ecosystem reflects the wilderness of more than 200 years ago when John Colter first explored the region.

Yellowstone was molded into a series of geysers and canyons resulting from cataclysmic volcanic activity more than 2 million years ago. Shaped by repeated eruptions, the park divides into three quadrants. On the western boundary lies a series of boiling-hot springs and steaming geysers in the Upper Geyser Basin, where more than 180 of the park’s total of 230 geysers heat the ground. Its most famous is Old Faithful, which jettisons about 8,000 gallons of boiling water to nearly 200 feet high, almost every 70 minutes.

The northern tract extends from Mammoth Hot Springs in the Lower Geyser Basin where the steaming water, loaded with calcium carbonate, forms white travertine terraces. The oldest geothermal area is the magnificent Grand Canyon where the spectacular Upper Falls and Lower Falls cascade into deep gorges. Yellowstone’s southern tract encompasses deciduous forests and the Yellowstone Lake at an elevation of 7,000 feet. The Continental Divide cuts a swath through the region where the Yellowstone River flows northeast and the Snake River drifts southwest.

The length of the 142-mile Grand Loop scenic drive can be done in a day but a minimum of three days to view the park is recommended. The park is always under threat of fire—the Yellowstone fires of 1988 destroyed some 793,000 acres in the Upper Geyser Basin.

The park has two entrances in Wyoming: north from Grand Teton National Park off Hwy 89/191/287, and east off Hwy 14/16/20 from Cody. There are three additional entrances from Montana with US-89 from Gardner open yearround to traffic. The other entrances are open from May to October. Snowcoaches transport visitors to the park in winter when Mammoth Hot Springs Lodge and Old Faithful Lodge are open.

Yellowstone National Park is serviced through Cody, Jackson, and Bozeman, Montana, which are all approximately 1 hour away. West Yellowstone’s airport across the Montana border is seasonal—it only opens during summer. While there is bus service to the park from Jackson and Cody, it is recommended that visitors rent a car for touring the park. A seven-day pass is available for a modest fee, allowing entry to both Grand Teton and Yellowstone National Parks. There are miles of cross-country ski trails along with outfitters offering horseback trips, chartered boats, and wildlife tours.