Grand Prismatic Spring

A Long History of Wonder

Fur trappers passing through the Midway Geyser Basin in 1839 described a "boiling lake" some 300 feet across, almost certainly this same spring, though it went formally undocumented for decades after. Geologists with the 1871 Hayden Geological Survey gave it the name Grand Prismatic Spring, for the rainbow of colors ringing its deep blue center. It remains the largest hot spring in the United States and the third largest in the world.

Getting There
Distance from Gardiner & North Entrance: 51 miles, 1.5–2 hours
Distance from West Yellowstone & West Entrance: 25 miles, ~45 minutes

Grand Prismatic Spring sits in the Midway Geyser Basin, about halfway between Madison Junction and Old Faithful. From the West Entrance at West Yellowstone, the drive runs through Madison Junction, the shortest route of the highlights here. From the North Entrance at Gardiner, it's a longer drive through Mammoth Hot Springs, Norris, and Madison Junction.

What You'll See

A half-mile boardwalk crosses the Firehole River and climbs past Excelsior Geyser, once the largest geyser on Earth and now a steaming, 200-foot-wide crater, before reaching Grand Prismatic itself, its blue center ringed by bands of orange, yellow, and green from heat-loving microbes living in the cooling water at its edges. The spring is best appreciated from above, since the boardwalk view can be obscured by its own steam on cooler mornings.

Visitor Tips

For the classic overhead photo, hike the Grand Prismatic Overlook Trail from the Fairy Falls trailhead, about a mile south of the main parking lot — it's roughly 1.6 miles round trip with some elevation gain, but delivers the view seen in almost every photo of the spring. This is one of the most crowded stops in the park, so arrive early or late in the day, and expect the parking lot itself to be a challenge in midsummer. Afternoon light tends to wash out the colors from the boardwalk, so late morning is often the best window if the overlook isn't in your plans.