Hike through massive hot springs formation

Travertine terraces at Mammoth Hot Springs.

Boardwalk trail
heads through
travertine terraces
at Yellowstone

Day hikers can walk through one of the world’s largest collection of travertine terraces on the Mammoth Hot Springs boardwalks at Yellowstone National Park.

A series of connected trails cut through the heart of the sprawling hot springs. A 0.8-mile loop allows you to see most of the major features. The best time to visit is late spring through early autumn; the road leading to the hot springs generally is closed December through April.

To reach the site, from the U.S. Hwys. 191/89 intersection near West Yellowstone, take the Grand Loop Road/U.S. Hwy. 89 east and north about 30 miles toward the Montana border. A couple of parking areas can be found off the highway's left/west side with walking paths leading from them into the hot springs area; among the best lots is the one immediately north of the road that turns off the highway to the horse corral.

The trail leaves from the lot's northwest corner. Where the asphalt path gives way to boardwalk, goes left/south. The boardwalk enters a massive stretch of white terrain that is noticeable from an airplane flying over. Fifty hot springs can be found in this area of the park.

The boardwalk passes the Jupiter Terrace with the Main Terrace south and west of it. These hot pools cascading over travertine terraces are a spectacular sight of steaming rocks and skeletal trees. The pools’ temperatures here can reach up to 163 degrees F.

Minerva Terrace
Next, the boardwalk passes a junction heading right/north; continue straight. The oft-photographed Minerva Terrace sits on the trail’s north side.

The terraces exists because a partially molten magma chamber sits far beneath the surface. As rain and snowmelt seeps into the ground, rock warmed by the magma in turn heats the water, which then shoots back upward through fissures.

As the water rises and meets carbon dioxide gas, it forms a weak acid that dissolves limestone buried underground. Upon reaching the surface, the carbon dioxide escapes into the air and leaves behind the calcium carbonate – aka as travertine – that forms the white terraces. More than two tons of calcium carbonate flow daily to the surface at Yellowstone.

At the second junction, take the boardwalk right/north. The Cleopatra Terrace is to the right/west. This part of the boardwalk loops around the Minerva Terrace.

Colorful terraces
As reaching the topic of the loop, pass the junction heading left/north. The scenic Palette Spring will then appear on the left/north side of the walkway.

Some of the terraces are colored orange, brown, red and even green. This is because of the algae – known as thermophiles – that lives in the warm pools on the surface.

At the next junction, take the stem trail going right; this leads you into the heart of the Minerva Terrace. After taking in the sites, head back to the junction and go straight/southeast.

From there, ignore the other trail junctions as this boardwalk heads back to the asphalt path that leads to your parking lot.

Learn about other great national park day hiking trails in my Best Sights to See at America’s National Parks guidebook.

Video of Mammoth Hot Springs Terraces

Day hikers can see the surface effects of a growing supervolcano on the Mammoth Hot Springs boardwalks at Yellowstone National Park.

The boardwalks weave through and around the Mammoth Hot Springs Terraces – hot pools cascading over travertine terraces are a spectacular sight in the park’s northern section. The disconnected boardwalks, accessible from Grand Loop Road, offer nearly 4 miles of otherwordly hiking:

The terraces would not exist if not for a vast chamber of molten rock, as known as magma, that sits several miles beneath the surface. With enough magma to fill the Grand Canyon 11 times over, even at that distance the chamber warms Yellowstone’s groundwater.

The heated water rises, working its way through fissures to about 50 hot springs at Mammoth. As doing so, it comes into contact with calcium carbonate, forming a weak acid that dissolves the limestone surface.

The result is a series of colorful, ever-changing terraces and pools of steaming hot water, in which temperatures can reach up to 163 degrees F.

Also see:
• Best trails for seeing Yellowstone’s natural wonders

Learn about trail guidebooks available in the Hittin’ the Trail series.

Best hikes for seeing Yellowstone's wonders

The Fairy Falls Trail passes the Grand Prismatic Spring
in Yellowstone National Park.

Try these 5 routes for geysers, wildlife, waterfalls

Among the best ways to see Yellowstone National Park’s major sights is via a day hike. Just five short trails will allow you to see each of the park’s highlights – geysers, hot springs, wildlife, waterfalls and canyons.

Old Faithful
Yellowstone’s most famous geyser erupts every 90 minutes or so, with water spewing more than 100 feet high for anywhere from 1.5 to 5 minutes. Most people see the geyser from the Old Faithful Boardwalk, so it’s a crowded path. Instead, watch it from the Observation Point Trail. There are some steep spots, but crowds are smaller, and you’ll see it from a unique vantage point.

Lamar Valley
Known as the “Serengeti of North America,” the valley contains the greatest collection of large animals in North America: bison and elk herds, grizzlies in the woods, wolf packs, black bears, and osprey and bald eagles in the skies. For the most intimate experience, hike a segment of the 5.3-mile Lamar Valley Trail (trailhead is east of Lamar Ranger Station). Dawn and dusk are the best times to see active animals.

Grand Prismatic Spring
The beautiful and oft-photographed hot spring boasts multicolored rings of algae. As the water temperature changes, so does the kind of thermophile living in it, resulting in a rainbow of colors. The prismatic spring is best seen from the 2.5-mile Fairy Falls Trail, which heads to a 197-foot waterfall and leaves from Grand Loop Road north of Old Faithful.

Grand Canyon of the Yellowstone
The Yellowstone River carved out this fantastic canyon below the 308-foot high Lower Falls. The 3.8-mile North Rim Trail runs along the canyon’s northwest wall. Parts of the trail are paved and there’s only 250 feet of elevation change.

Bechler Basin waterfalls
Located in the park’s southwest corner, the basin boasts dozens of waterfalls. From the Bachler Ranger Station, try the 3-mile round trip Cave Falls Trail, which follows the Falls River to Bechler Falls. The hike is best done in August and September when the mosquito population is the lowest, as the bogs are drier.

Mammoth Hot Springs Terraces
These hot pools cascading over travertine terraces are a spectacular sight in the park’s northern section. The disconnected Mammoth Hot Springs boardwalks, accessible from Grand Loop Road, weaves through and around the springs for nearly 4 miles of hiking. The pools’ temperatures here can reach up to 163 degrees F.

Learn about other great national park day hiking trails in my Best Sights to See at America’s National Parks guidebook.

Photos, maps of Yellowstone National Park’s Mammoth Hot Springs boardwalk trails

Day hikers can walk through one of the world’s most fantastic collection of travertine terraces on the Mammoth Hot Springs boardwalks at Yellowstone National Park.

To reach the site, from the U.S. Hwys. 191/89 intersection near West Yellowstone, take the Grand Loop Road/U.S. Hwy. 89 east and north about 30 miles toward the Montana border. A couple of parking areas can be found off the highway's left/west side with walking paths leading from them into the hot springs area.

Sunrise over the hot springs (photo courtesy of Yellowstone NPS); a series of connected trails cut through the heart of the geological feature:

Overview map of Mammoth Hot Springs with key geological features (illustration courtesy of Wikipedia):

Among the best lots the park is the one immediately north of the road that turns off the highway to the horse corral. A 0.8-mile hike (outlined in yellow) then can be followed through the hot springs:

The white terraces are created by dissolved limestone that crystalizes as the hot spring brings it to the surface:

Sunlight low on the horizon casts a warm glow across the terraces:

Some of the terraces can grow quite tall. They are several thousand years in the making:

Steam from the hot springs roils off the terraces:

Looks like a scene out of winter, but this photo was taken in summer:

Brown algae that thrives in hot environments grows on some of the terraces; other algae colors found at the hot springs are red, orange and green:

Learn about other great national park day hiking trails in my Best Sights to See at America’s National Parks guidebook.