Grand Prismatic Spring

The center of Grand Prismatic is a deep, clear blue, the color of very pure, very hot water, near boiling as it rises from below. That water is too hot for most life, which is why the middle stays a sterile, brilliant blue.

As the water spreads outward and cools, it enters temperature bands where different heat-loving microbes can survive, and each builds a mat of a different color. Cooler outer rings glow orange and rust with pigments the microbes make to shield themselves from the sun, warmer inner rings turn yellow and green, and the result is the ringed rainbow that gives the spring its name. The colors are richer in summer sun and fade toward green in the cooler, lower-light months.

Yellowstone sits atop one of the largest volcanic systems on Earth, a hot spot where molten rock lies relatively close to the surface. Rain and snowmelt sink deep, are heated, and rise back up through cracks, feeding the park's thousands of geysers, hot springs, mud pots, and steam vents. Grand Prismatic is simply the grandest of the springs.

The whole Midway Geyser Basin steams and hisses around it. The runoff from the spring pours over broad orange terraces down to the Firehole River, and Excelsior Geyser Crater, a giant collapsed spring, pumps thousands of gallons a minute into the river nearby. It is a place where the raw machinery of the planet is on full, quiet display.

A boardwalk loop from the Midway Geyser Basin parking area leads right out across the terraces and along the edge of Grand Prismatic. Up close you feel the heat and see the vivid microbial mats, though from ground level the steam often hides the full shape of the pool.

For the postcard view, the one that shows the whole rainbow eye at once, take the short but steeper hike to the Grand Prismatic Overlook, reached from the Fairy Falls trailhead just to the south. It climbs a forested hillside to a platform looking down on the spring, and it is worth the extra walk.

Long before it was a park, this country was known and traveled by many tribes, among them the Shoshone, whose Tukudika or Sheepeater bands lived in the Yellowstone high country. Their descendants and other tribes retain deep ties to this land.

Bison often graze the warm ground and thermal meadows near the basin, and it is vital to keep well back from them. Elk, bald eagles, and waterfowl move along the Firehole. Summer is warm, crowded, and best for the colors, while spring and fall are quieter, cooler, and often steamier. Roads through this part of the park close in winter, when the basins can be reached only by guided snowcoach or skis.

The closest Boutel™ stays, so you can turn this stop into an overnight. Each is a place we chose through independent editorial review, never a paid placement.

Grand Prismatic Spring, in the Midway Geyser Basin of Yellowstone National Park in northwestern Wyoming, is the largest hot spring in the United States and one of the most beautiful and famous in the world. Renowned for its stunning, vivid colors, the spring displays brilliant bands of blue, green, yellow, orange, and red radiating outward from its deep blue center, created by different heat-loving microorganisms living in the varying temperatures of the water. Enormous and steaming, ringed by these rainbow hues, Grand Prismatic Spring is a breathtaking and iconic sight. Viewable from boardwalks and an overlook trail, it is one of Yellowstone's most spectacular and photographed natural wonders.

Grand Prismatic Spring gets its spectacular rainbow colors from different species of heat-loving microorganisms, called thermophiles, that live in bands around the spring where the water is different temperatures. The center of the spring is extremely hot and a deep, sterile blue, while moving outward as the water cools, different microbes thrive and produce pigments that create the vivid rings of green, yellow, orange, and red. The colors are often more vibrant in summer. This natural, living palette of microorganisms adapting to the temperature gradient is what gives Grand Prismatic Spring its extraordinary and beautiful colors, making it one of Yellowstone's most stunning features.

You can see Grand Prismatic Spring up close from the boardwalks in the Midway Geyser Basin, which bring you right alongside the enormous, steaming, colorful spring, though from ground level the steam and size can make it hard to appreciate the full rainbow. For the best view of the spring's stunning colors and scale, hike the Grand Prismatic Overlook Trail, a short uphill walk from a nearby trailhead that leads to an elevated viewpoint offering a spectacular bird's-eye view of the whole spring. Combining the boardwalk for a close look and the overlook for the full colorful vista gives the best experience.

This is critical: stay on the boardwalks and designated trails at all times, as the ground around the spring can be thin over scalding, boiling water, and leaving the trail has caused severe burns and deaths in Yellowstone's thermal areas. Never touch the thermal water or approach the spring off the boardwalk. Keep a safe distance from any wildlife. Watch children closely. Respecting the boardwalk barriers and the extreme danger of the thermal features is essential for a safe visit to Grand Prismatic Spring and the surrounding geyser basin.

Grand Prismatic Spring is in the Midway Geyser Basin of Yellowstone National Park in northwestern Wyoming, near the Grand Prismatic Overlook Trail, the famous Old Faithful and Upper Geyser Basin, the park's many other geysers and hot springs, and within reach of the park's other wonders and gateway towns. That makes Grand Prismatic Spring a must-see stop to combine with Old Faithful, the geyser basins, and the many other attractions of Yellowstone National Park on a visit to Wyoming.