Watching Old Faithful Geyser erupt is a Yellowstone National Park tradition. People from all over the world have journeyed here to watch this famous geyser. The park’s wildlife and scenery might be as well-known today, but it was the unique thermal features like Old Faithful Geyser that inspired the establishment of Yellowstone as the world’s first national park in 1872.

Old Faithful is one of nearly 500 geysers in Yellowstone and one of six that park rangers currently predict. It is uncommon to be able to predict geyser eruptions with regularity and Old Faithful has lived up to its name, only lengthening the time between eruptions by about 30 minutes in the last 30 years.

Thermal features change constantly and it is possible Old Faithful may stop erupting someday. Geysers and other thermal features are evidence of ongoing volcanic activity beneath the surface and change is part of this natural system. Yellowstone preserves the natural geologic processes so that visitors may continue to enjoy this natural system.

The earliest intact archeological deposits in the park have been found at a site on the shore of Yellowstone Lake. The site was excavated because it was at risk of erosion, and revealed evidence of a 9,350-year-old camp where several families appear to have spent time. People probably used this area in the summer while hunting bear, deer, bighorn, and rabbits, and perhaps making tools and clothes. Artifacts dating to 3,000 years ago have also been discovered on islands in the lake, leading some archeologists to speculate that indigenous peoples used watercraft to travel there.

Walk on boardwalks above the steaming hydrothermal features or take a drive around the vibrant travertine terraces. In the winter, ski or snowshoe among the whiffs of sulfur along the Upper Terraces.

The hydrothermal features at Mud Volcano are primarily mudpots and fumaroles because the area is situated on a perched water system with little water available. Thanks to thermophiles, the vapors are rich in sulfuric acid that breaks the surrounding rock down into clay. Hydrogen sulfide gas is present deep in the earth at Mud Volcano. As this gas combines with water and the sulfur is metabolized by cyanobacteria, a solution of sulfuric acid is formed that dissolves the surface soils to create pools and cones of clay and mud. Along with hydrogen sulfide, steam, carbon dioxide, and other gases explode through the layers of mud. A series of shallow earthquakes associated with the volcanic activity in Yellowstone struck this area in 1978. Soil temperatures increased to nearly 200°F (93°C).

The original bridge was built in 1902. It was a rough-hewn corduroy log bridge with a slightly different alignment than the current bridge. The existing bridge was built in 1937. Fishing Bridge was historically a tremendously popular place to fish. Angling from the bridge was quite good, due to the fact that it was a major spawning area for cutthroat trout. However, because of the decline of the cutthroat population (in part, a result of this practice), the bridge was closed to fishing in 1973.

Hayden Valley is a great place to view wildlife. Grizzly bears may be seen in the spring and early summer preying upon newborn bison and elk calves. Bison are often seen in the spring all the way through the fall rut. Coyotes and foxes are often seen in the valley. Ducks, geese, and American white pelicans cruise the river, while a variety of shore birds may be seen in the mud flats at Alum Creek. Keep an eye out for bald eagles, northern harriers, and sandhill cranes.

Safety Tip: Do not approach or surround bears or wolves on foot within 100 yards (91 m) or other wildlife within 25 yards (23 m). Maintain a safe distance from all wildlife.

Two different trailheads lead to Fairy Falls, which at 200 feet (61 m) high is one of Yellowstone’s most spectacular waterfalls.

The northern trailhead starts at the end of the Fountain Flat Drive and follows an old road across meadows and near hydrothermal features. This is a 6.7-mile (10.7-km) hike.

The southern trailhead starts at the Fairy Falls parking area and follows an old road along the edge of the Midway Geyser Basin. This is a 5.4-mile (8.6-km) hike. Also along this trail is the side-hike up to the Grand Prismatic Overlook Trail to a wonderful view of Grand Prismatic Spring and the rest of the Midway Geyser Basin.

Hayden Valley is located six miles north of Fishing Bridge Junction and Pelican Valley is situated three miles to the east of the junction. These two vast valleys comprise some of the best habitat in the lower 48 states for viewing wildlife like grizzly bears, bison, and elk.

There are a lot of hydrothermal wonders to discover in this region, from small geysers and fumaroles to more well-known mudpots and hot springs. This is also a popular area in the summertime, so be prepared for crowded parking areas, or plan to visit during off-hours.

Terrace Springs, Fountain Paint Pot, Firehole Lake Drive, Midway Geyser Basin

With a peak elevation of 10,219 feet (3,115 m) and panoramic views for about 20 to 50 miles (32 to 80 km), Mount Washburn is a popular day-hiking destinations. It is located just a few miles north of Canyon Village. Mount Washburn is the remnant of volcanic activity that took place long before the formation of the present canyon and named for General Henry Washburn, leader of the 1870 Washburn-Langford-Doane Expedition.

The first major entrance for Yellowstone was at the north boundary. Before 1903, trains would bring visitors to Cinnabar, Montana, which was a few miles northwest of Gardiner, Montana, and people would climb onto horse-drawn coaches there to enter the park.

In 1903, the railway finally came to Gardiner, and people entered through an enormous stone archway. Robert Reamer, a famous architect in Yellowstone, designed the immense stone arch for coaches to travel through on their way into the park. At the time of the arch’s construction, President Theodore Roosevelt was visiting the park. He consequently placed the cornerstone for the arch, which then took his name. The top of the Roosevelt Arch is inscribed with “For the benefit and enjoyment of the people,” which also appears in the National Park Service Organic Act of 1916.

There are three side drives in this region. All of them are open only during the summer season, with Blacktail Plateau Drive opening the latest due to being in a bear management area. The first, the Old Gardiner Road, is an old, unpaved, one-way road going from Mammoth Hot Springs to Gardiner, Montana.

Upper Terrace Drive is a short, one-mile (1.6-km) loop drive with a few parking areas along the way. The drive leads you to views of the Main Terraces of Mammoth Hot Springs, views of Fort Yellowstone and the Gardner River, and right up to hydrothermal features like Orange Spring Mound.

Blacktail Plateau Drive is an unpaved, six-mile (9.7-km) one-way road that meanders through alpine forests and meadows. It provides a more rustic way to travel to Tower–Roosevelt, and gives opportunities to see wildlife and take in the beautiful alpine scenery.

Firehole Canyon Drive follows the Firehole River upstream from Madison Junction to just above Cascades of the Firehole. The drive takes you past 800-foot thick lava flows and to a viewing area of Firehole Falls, a 40-foot (12.2-m) waterfall.

Also along the drive is an unstaffed swimming area, which is very popular in the warmest part of the summer season. Learn more about the hazards of swimming and soaking in Yellowstone.

Norris is one of the hottest and most acidic of Yellowstone’s hydrothermal areas. It is part of one of the world’s largest active volcanoes. Many hot springs and fumaroles here have temperatures above the boiling point (200ºF / 93ºC).

Water fluctuation and seismic activity often change features. Norris is near the intersection of three major faults. One runs from the north; another runs from the west. These two faults intersect with a ring fracture from the Yellowstone Caldera eruption 640,000 years ago. These conditions helped to create this dynamic geyser basin.

Notes: Thermal activity throughout this entire area. Stay on the boardwalks and designated trails at all times.

Located just north of Norris on the Norris–Mammoth section of the Grand Loop Road, Roaring Mountain is a large, acidic thermal area that contains many fumaroles. In the late 1800s and early 1900s, the number, size, and power of the fumaroles was much greater than today.

The Gibbon River flows from Wolf Lake through the Norris area and meets the Firehole River at Madison Junction to form the Madison River. Both cold and hot springs are responsible for the majority of the Gibbon River’s flow. Brook trout, brown trout, grayling, and rainbow trout live in the Gibbon River. The Gibbon River is fly-fishing only below Gibbon Falls.

Yellowstone, as a whole, possesses close to 60 percent of the world’s geysers. The Upper Geyser Basin is home to the largest numbers of this fragile feature found in the park. Within one square mile there are at least 150 of these hydrothermal wonders. Of this remarkable number, only five major geysers are predicted regularly by the naturalist staff. They are Castle, Grand, Daisy, Riverside, and Old Faithful. There are many frequent, smaller geysers to be seen and marveled at in this basin as well as numerous hot springs and one recently developed mudpot (if it lasts).

Lone Star Geyser erupts about every three hours. There is a logbook, located in a cache near the geyser, for observations of geyser times and types of eruptions. This is a 4.8 mile (7.7 km), easy there-and-back hike or bike that follows the Firehole River to the geyser. The trailhead is east of Kepler Cascades pullout, 3.5 miles (5.6 km) southeast of the Old Faithful overpass on Grand Loop Road.

Lone Star erupts 30–45 feet (9–14 m) about every three hours. If you witness an eruption, please note the time and report it at the Old Faithful Visitor Education Center. Biking is not permitted beyond a barrier near the geyser.

• Fairy Falls Trail
• Howard Eaton Trail (Old Faithful Area)
• Sentinel Meadows & Queen’s Laundry Trail
• Grand Prismatic Overlook Trail
• Lone Star Geyser Trail
• Mallard Lake Trail
• Mystic Falls Trail
• Observation Point Trail

The 132-foot (40-m) drop of Tower Creek, framed by eroded volcanic pinnacles has been documented by park visitors from the earliest trips of Europeans into the Yellowstone region. Its idyllic setting has inspired numerous artists, including Thomas Moran. His painting of Tower Fall played a role in the establishment of Yellowstone National Park in 1872.

The nearby Bannock Ford on the Yellowstone River was an important travel route for early Native Americans, as well as for early European visitors and miners up to the late 19th century.

Tower Fall is visible from an overlook a short walk from the Tower General Store.

West Thumb Geyser Basin, including Potts Basin to the north, is the largest geyser basin on the shores of Yellowstone Lake. The heat source of the hydrothermal features in this location is thought to be relatively close to the surface—only 10,000 feet (3000 m) down!

The West Thumb of Yellowstone Lake was formed by a large volcanic explosion that occurred approximately 150,000 years ago (125,000–200,000). The resulting collapsed volcano later filled with water forming an extension of Yellowstone Lake. The West Thumb is about the same size as another famous volcanic caldera, Crater Lake in Oregon, but much smaller than the great Yellowstone Caldera which formed 600,000 years ago. It is interesting to note that West Thumb is a caldera within a caldera.

Ring fractures formed as the magma chamber bulged up under the surface of the earth and subsequently cracked, releasing the enclosed magma. This created the source of heat for the West Thumb Geyser Basin today.