Yellowstone National Park

Old Faithful

Rangers forecast this geyser's eruptions reliably enough that crowds gather on the surrounding boardwalk to watch, with each eruption usually lasting three to four minutes. Of the nearly 500 geysers in the park, rangers currently predict just six, and this is one of them; its interval has grown by only about half an hour over three decades. Boardwalks wind through the Upper Geyser Basin, where hundreds more geysers and hot springs steam and bubble. The historic district, including Old Faithful Inn, preserves rustic architecture from early visitor lodging, and the Old Faithful Visitor Education Center explains the volcanic forces at work below. Trails such as Observation Point and Lone Star Geyser offer calmer vantage points, skiers and snowshoers explore the area in winter, and the warm basins give bison, coyotes and ravens a home in every season.

Grand Prismatic

Rainbow-colored bacterial mats spread outward from a steaming azure pool at the world's largest hot spring, giving the ground a sunburst look when seen from above. The spring sits in Midway Geyser Basin, which also holds Excelsior, the world's largest geyser. Boardwalks lead past both features for a ground-level view of the steam and color. For the elevated view many photographers come for, start at the Fairy Falls Trailhead, about a mile south of the basin. The Grand Prismatic Overlook Trail is an easy hike of about 0.6 miles each way. It follows the Firehole River on flat ground, then gains roughly 105 feet to a hillside overlook above the spring and the basin. Elk sometimes graze near the water. Off-trail travel is prohibited throughout the area, including on the hills above the spring.

West Thumb

Mudpots, boiling springs and geysers crowd the edge of Yellowstone Lake here, some of them draining hot water straight into the cold lake. A short boardwalk through the West Thumb Geyser Basin passes colorful hot springs and dormant lakeshore geysers. It starts at the West Thumb Information Station, a 1925 ranger station with a ranger desk, park store and programs. The bay got its name from 1870 explorers who thought the lake looked like an outspread hand, with this bay as the thumb. The Lake Overlook Trail climbs to a meadow facing the bay and the Absaroka Mountains. Watch for bald eagles and osprey diving for cutthroat trout, along with elk, loons and ducks. Paddlers launch from Grant Village Marina. Native American hearth sites along the shore show that people once traveled, camped and gathered food here.

Norris Geyser Basin

This is the park's hottest, oldest and most dynamic thermal area, sitting where major faults meet a ring fracture from an ancient caldera, so its features shift often with earthquakes and changing water levels. Most of the water is acidic, and few features stay below boiling. Boardwalks and paths cross its two areas, Porcelain Basin and Back Basin. Porcelain Basin, bare of trees, is reached by a 3/4-mile walk and offers a mix of sound, color and smell. The wooded Back Basin Trail leads to Steamboat Geyser, the world's tallest, whose unpredictable eruptions reach 300 to 400 feet. Acidic Echinus Geyser is another favorite. On the ridge above, the stone-and-log Norris Geyser Basin Museum and Information Station hosts rangers and programs. The nearby Museum of the National Park Ranger, in a restored soldier station, traces ranger history.

Mammoth Hot Springs

Hot water rising through ancient limestone dissolves calcium carbonate and deposits it as the white, chalky travertine terraces that step down the hillside. Travertine grows far faster than the sinter of other thermal basins, so the formations change quickly, and algae stain the warm pools brown, orange, red and green. Boardwalks pass the steaming features, and trails of varied difficulty explore the surroundings. Upper Terrace Drive, a one-mile loop, reaches Orange Spring Mound and looks over the Main Terraces, Fort Yellowstone and the Gardner River. The fort, a historic US Army post, offers a self-guiding tour on the Army's early role protecting the park, and the Roosevelt Arch belongs to the same historic district. Albright Visitor Center has wildlife exhibits, elk often graze the lawns around park headquarters, and winter brings skiing and snowshoeing on the Upper Terraces.

Madison

Here the Gibbon and Firehole rivers join to form the Madison River, at a junction where people have camped for at least 10,000 years, leaving obsidian flakes and campfire remnants. The National Park Mountain story claims explorers camped here in 1870 and dreamed up the national park idea, but it isn't true. Read it at the Madison Information Station and Trailside Museum, a stone and log "parkitecture" building with ranger programs and a patio view. Madison Campground, among the park's largest, sits by meadows that fill with wildflowers and bison in early summer and ring with bugling elk in autumn. The Purple Mountain Trail climbs 1,500 feet to views of the Gibbon and Madison rivers. Nearby, 84-foot Gibbon Falls spills over remnants of the caldera rim, and toward Norris, Artists Paintpots holds colorful hot springs and mud pots.

Lake Village

This lakeside village looks out over Yellowstone Lake, the biggest lake in North America sitting above 7,000 feet. Its waters plunge past 400 feet, and its shoreline runs for 141 miles. The historic Lake Yellowstone Hotel anchors the area, pairing lake vistas with a dining room, a deli and a bar. Lake Lodge Cabins offer another place to stay, and the lodge cafeteria serves casual meals. The Lake General Store adds a concession and ice cream counter, while Wylie's Canteen and gift shops round out the options. Practical services include the Lake Medical Clinic and a post office. Bridge Bay Campground lies a few miles southwest along the Grand Loop Road beside Bridge Bay Marina, and from there campers can see the Absaroka Range climbing beyond the lake's far eastern side.

Lamar Valley

This wide valley sits off in the park's isolated northeast corner, and it has drawn wolf watchers ever since wolves were brought back in 1995. Large herds of bison and elk spend summer here, drawing wolves and grizzly bears, and black bears, pronghorn, coyotes and bighorn sheep also appear. Sightings peak in early morning and evening. Keep 100 yards from bears and wolves, 25 from other animals. The valley lies about an hour's drive from Mammoth Hot Springs, and much of the wildlife can be spotted from the road. The Lamar Buffalo Ranch, visible from the drive, recalls an early 20th-century effort to rebuild a dwindling bison herd. For a short walk, an uphill trail climbs through forest to Trout Lake. Carry bear spray and hike in a group.

Hayden Valley

An arm of Yellowstone Lake once filled this broad valley, and the clay-rich glacial till over its old lake sediments keeps water from soaking in, leaving a marshy floor with few trees. Bison are the main draw, seen from spring through the fall rut and sometimes gathered in large herds right beside the road. Grizzly bears hunt newborn bison and elk calves in spring and early summer, and coyotes and foxes are common sights. Birders can find ducks, geese and American white pelicans floating on the river, shorebirds feeding on the Alum Creek mud flats, and bald eagles, northern harriers and sandhill cranes nearby. The road through the valley links Canyon Village and Yellowstone Lake, so it pairs easily with canyon viewpoints like Artist Point. Stay at least 100 yards from bears and 25 yards from other wildlife.