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.

Watch eruptions from the Old Faithful viewing area or along the boardwalks that weavearound the geyser and through the Upper Geyser Basin.

The Grand Prismatic Spring in Yellowstone National Park is the largest hot spring in the United States, and the third largest in the world, after Frying Pan Lake in New Zealand and Boiling Lake in Dominica. It is located in the Midway Geyser Basin.

Grand Prismatic Spring was noted by geologists working in the Hayden Geological Survey of 1871, and named by them for its striking coloration. Its colors match most of those seen in the rainbow dispersion of white light by an optical prism: red, orange, yellow, green, and blue.

This one-mile (1.6 km) trail offers a scenic loop through a partially burned lodgepole pine forest, leading across a wet meadow via a boardwalk. The trail features an array of colorful hot springs, mudpots, and small geysers, creating a mesmerizing hydrothermal area. Ensure to remain on designated trails and boardwalks to safely navigate the terrain and watch for flying mud near the mudpots.

Initially, the trail is relatively flat from the parking area to the hydrothermal features, transitioning over bare ground. The lower portion of the loop combines boardwalk sections with bare ground paths, while the back portion ascends with steps and steep grades to reach the more active mudpots.

Hydrothermal features here fall into two main categories: those with ample water, such as hot springs and geysers, and those with limited water, like mudpots and fumaroles. This area is renowned for its captivating mudpots, which provide an intriguing display of splattering mud, accompanied by a symphony of unique sounds. The mudpots are acidic, benefiting from a limited water supply. Microorganisms in the mudpots use hydrogen sulfide, rising from deep within the earth, as an energy source, converting it into sulfuric acid. This chemical process breaks down rock into wet clay mud, contributing to the area's distinctive rotten eggs smell. Various gases escaping through the wet clay mud cause bubbling, with mudpot consistency and activity varying with the seasons and precipitation.

Mammoth Hot Springs is a remarkable and sprawling complex of travertine hot springs located within the breathtaking expanse of Yellowstone National Park, conveniently situated adjacent to Fort Yellowstone. Over the span of thousands of years, the interplay between hot water from these springs and the environment has resulted in the cooling and deposition of calcium carbonate, with more than two tons of this mineral flowing into Mammoth Springs on a daily basis. Although the springs are found outside the main caldera of the park, their geothermal energy is intricately linked to the same magmatic system that fuels other geothermal features throughout Yellowstone.

The hot water feeding into Mammoth originates from the Norris Geyser Basin, embarking on a journey underground where it moves through limestone via a fault line that runs parallel to the Norris-to-Mammoth road. This limestone plays a crucial role, as it is the primary source of the calcium carbonate deposited at the springs. As the superheated water travels towards Mammoth, it loses heat and cools to approximately 170 °F (80 °C), creating a unique environment where diverse algae thrive, adding vibrant shades of brown, orange, red, and green to the characteristic travertine formations.

The thermal activity at Mammoth Hot Springs is extensive and dynamic, with notable variations occurring over the course of decades. The area's impressive Terrace Mountain is renowned as the world's largest carbonate-depositing spring, showcasing the power of geothermal processes. Among its many features, the Minerva Terrace stands out as the most famous, drawing visitors from around the globe. Despite the challenges posed by recent earthquakes that have altered the spring vent's location, the terraced formations continue to exhibit their stunning beauty and geological significance, captivating all who witness them.

Starting at the Dunraven Pass Trailhead, hikers begin their ascent of the majestic Mount Washburn, traversing a well-maintained trail that offers spectacular panoramic views of the surrounding landscape. As you make your way upward, keep your eyes peeled for the elusive bighorn sheep that are often spotted in this area, as well as the vibrant wildflowers that add splashes of color to the rugged terrain. It's essential to stay on the designated trail to protect and preserve the delicate alpine vegetation that thrives here, as any foot traffic off the path can lead to irreversible damage. Upon reaching the summit, you can take a moment to revel in the breathtaking views that stretch for miles. 

Additionally, don't miss the chance to explore the interpretive exhibits located inside the shelter at the base of the historic fire lookout, where you can learn more about the area's natural history and its significance. The trailhead conveniently begins at the parking lot at Dunraven Pass, which is located 4.5 miles (7.2 km) north of Canyon Junction, making it easily accessible for adventurers eager to experience this stunning hike.

The Upper and Lower Yellowstone River Falls are incredibly popular tourist attractions in Yellowstone National Park—and for good reason. Conveniently located just off the main highway that connects North Rim Drive and South Rim Drive in the Canyon Area, the Brink of the Upper Falls presents a breathtaking drop of 109 feet into the magnificent and storied Grand Canyon of the Yellowstone. Unlike the more frequently visited Lower Falls, the Upper Falls often sees somewhat less traffic, allowing for a more serene experience. Visitors can enjoy several roadside viewpoints that make access easy and enjoyable. 

On the other hand, the Lower Yellowstone River Falls, which is the most famous waterfall in the park, boasts an impressive 308-foot drop and offers multiple postcard-worthy vantage points for photography enthusiasts. Due to its popularity, the viewing platforms are almost always bustling with eager visitors, so it's wise to plan ahead for crowds. A favorite spot among tourists is Artist’s Point, which provides a classic, breathtaking view of the falls without requiring any lengthy hiking. Truly, this waterfall is a must-see for anyone traveling through Yellowstone, as it encapsulates the natural beauty and grandeur that the park is renowned for.

The Grand Canyon of the Yellowstone River is a vibrant showcase of the park's geologic history, marked by colorful landscapes and steam from hydrothermal features dotting its walls. The awe-inspiring Upper and Lower Falls of the Yellowstone River enhance this natural marvel. Viewpoints and trails offer diverse experiences across different times and seasons.

Formed primarily by the erosion of the Yellowstone River, the canyon's detailed geology is complex. Following a massive volcanic eruption about 600,000 years ago, the resulting lava flows and faulting from caldera doming accelerated erosion. Glacial deposits, now mostly eroded, used to cover the area, but left minimal traces behind.

Once a geyser basin, the area below Lower Yellowstone Falls was shaped by rhyolite lava flows and faulting. Geothermal activity altered the rhyolite, making it softer and prone to erosion. Active geysers and hot springs continue to reveal this thermal legacy.

Clear Lake, south of the canyon and fed by hot springs, also reflects this geothermal history. At the last glacial period's end, approximately 14,000-18,000 years ago, melting ice dams unleashed floods that shaped the canyon’s V-shaped valley, a hallmark of river erosion.

The canyon’s striking colors result from hydrothermal changes in iron-rich rhyolite rock, resembling rust as environmental exposure alters these compounds, predominantly producing yellow hues.

Lamar Valley-Be sure to keep your eyes peeled and your binoculars handy for your travels through the Lamar Valley. This river valley, bookended by mountain ranges, is home to herds of elk, bison, grizzlies, several packs of wolves, and a variety of bird species. Accessible via car year-round, this valley is a prime location for wildlife viewing, especially during the early morning or late evening hours.

Also located in the valley is the Lamar Buffalo Ranch Historic District. Established in 1907 when bison were moved from Fort Yellowstone to the valley, buffalo ranching operations continued at Lamar until the 1950s. Today, the Yellowstone Association offers naturalist-led programs from this historic ranch

Yellowstone Lake is a remarkable high-elevation body of water located in Yellowstone National Park. At an elevation of 7,732 feet (2,357 m), it is the largest high elevation freshwater lake (above 7,000 ft) in North America, covering around 136 square miles with 110 miles of picturesque shoreline. The lake boasts impressive depths, averaging 139 feet with maximum depths exceeding 394 feet. In winter, the lake typically freezes by early December, with ice remaining until late May or early June. 

Average water temperatures linger around a chilly 41°F (5°C), making swimming hazardous due to short survival times of just 20-30 minutes. The lake’s icy waters host the largest population of wild cutthroat trout in North America. Originally linked to the Pacific Ocean, fish such as the cutthroat trout found their way to this lake across the Continental Divide. However, the introduction of non-native lake trout poses a threat to these indigenous fish.

Draining north through the Yellowstone River, the lake's ecology and unique geological history fascinate visitors and scientists alike. Whether in icy winter months or thawing summers, Yellowstone Lake offers a compelling glimpse into North America's natural wonders.

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).

Just north of Old Faithful are two smaller basins that are worth a visit. Both basins have parking lots, or are accessible by foot via the trail network through the Upper Geyser Basin. Black Sand Basin is northwest of Old Faithful and has several enjoyable hydrothermal features, from the rather active Cliff Geyser to the chromatic Rainbow Pool and Sunset Lake.

Further north of Old Faithful is Biscuit Basin, named after the biscuit-shaped geyserite formations that can still be seen around parts of the majestic Sapphire Pool. There are also some enjoyable surprises along the boardwalk like Jewel Geyser, as well as the start of the Mystic Falls Trail at the far end of the boardwalk loop. Biscuit Basin is closed for the remainder of summer 2024 due to a hydrothermal explosion.

This small yet captivating geyser basin along the Firehole River showcases some of Yellowstone National Park's most impressive hydrothermal features. Among these marvels is the renowned Excelsior Geyser Crater, a massive hot spring that spans an impressive 200 feet by 300 feet (61 meters by 91 meters). Continuously steaming, it releases over 4,000 gallons (15,142 liters) of water every minute into the Firehole River, creating a dynamic and fascinating natural display.

Adding to the basin's splendor is the Grand Prismatic Spring, Yellowstone's largest hot spring. This chromatic wonder measures 370 feet (113 meters) in diameter and exceeds 121 feet (37 meters) in depth. Its vibrant colors, resulting from microbial mats around the mineral-rich water, offer a stunning visual spectacle. Together, these features encapsulate the geothermal power and beauty that make Yellowstone a unique and treasured national park, attracting visitors from around the globe to witness its awe-inspiring natural phenomena.

Lone Star Geyser is a captivating natural feature in Yellowstone National Park, known for its predictable and majestic eruptions approximately every three hours. Nestled along the scenic Firehole River, this geyser provides an exhilarating experience for those willing to embark on the 4.8-mile (7.7 km) round-trip hike or bike ride to witness its splendor. The trailhead begins east of the Kepler Cascades pullout, situated 3.5 miles (5.6 km) southeast of the Old Faithful overpass on Grand Loop Road.

Upon reaching Lone Star Geyser, visitors are treated to impressive eruptions that soar between 30 and 45 feet (9 to 14 meters) into the air, accompanied by dramatic sprays of boiling water and steam. A unique feature at this geyser is the logbook, stored in a nearby cache, where observers can record eruption times and types. This valuable information contributes to the understanding of the geyser's behavior.

Visitors can enhance their visit by reporting eruption details to the Old Faithful Visitor Education Center. While biking is an enjoyable way to approach the geyser, it is important to note that bikes are prohibited beyond a designated barrier near the geyser, ensuring preservation and safety for all visitors.

Yellowstone National Park is home to a collection of breathtaking waterfalls, each offering unique beauty and charm. 

Firehole Falls, just a short drive from West Yellowstone, is one of the park’s most accessible and stunning spots. Located off the scenic Firehole Canyon drive, these falls see the Firehole River gracefully meander before plunging 40 feet down jagged cliffs.

Tower Falls, plunging 132 feet into the Yellowstone River, is another renowned waterfall situated between Tower-Roosevelt and Canyon Village. Easily accessible from a spacious parking area, this waterfall is framed by majestic rocky pinnacles and is a popular destination, so early arrival is recommended for a tranquil visit.

Gibbon Falls, nestled between Madison and Norris Junctions, features an 84-foot cascade into a crystal-clear pool, all within a quintessential Yellowstone landscape of rocky cliffs and pine trees. Visitors can enjoy this stunning view after a short walk from the road.

Kepler Cascades, located just south of Old Faithful, offers a more secluded experience. The Firehole River narrows and drops dramatically into a rocky pool surrounded by pine trees, with a cozy overlook providing a serene escape from busier areas.

For those seeking solitude, Undine Falls, named after mythical sprites, offers a peaceful setting along the highway between Mammoth Hot Springs and Tower-Roosevelt. This 60-foot triple-plunge waterfall is set amid Yellowstone's classic rock-lined landscapes and is one of the less-traveled waterfalls in the park.

The famous Lower Yellowstone River Falls, with its awe-inspiring 308-foot drop, is a must-see. Located between North and South Rim Drives, these falls along with the Upper Falls, which drops 109 feet, offer postcard-worthy views. While often crowded, locations like Artist’s Point provide spectacular vantage points without needing a hike.

To fully appreciate the beauty of Yellowstone's waterfalls, plan to start your day early to avoid crowds. Many falls are accessible without hiking, but the extra effort can offer a more personal and tranquil experience, showcasing the hidden wonders of Yellowstone.