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Hot spring · West Yellowstone, Montana
Grand Prismatic Spring
The largest hot spring in the United States, with rings of blue, green, yellow and orange color, in the Midway Basin; also visible from the Fairy Falls trail overlook.
Illustrative images. The pictures in this guide are illustrations based on the real place, not photographs, and may differ from it.
Discover
About Grand Prismatic Spring
The Grand Prismatic is the largest hot spring in the United States and the third largest in the world, about 110 meters in diameter. It sits in the Midway Geyser Basin, beside the Firehole River, roughly 15 km north of Old Faithful.
The center of the spring is deep blue because of depth and very hot water. Around it, rings of microorganisms that live at different temperatures paint the rim green, yellow, orange and red, and steam rises from the surface on cold days. The wooden boardwalk in Midway Basin runs along the edge of the spring and past the Excelsior Geyser Crater, a crater that spills hot water into the river.
To see the colors from above, the Fairy Falls trail, which starts at a parking area about 2 km to the south, leads about 1 km to an overlook on a ridge above the spring. The trail continues to the waterfall, for a total of roughly 8 km round trip.
Before you go
Practical information
Cidade Turismo reviews its information regularly, but something may have changed. Check with the place before planning your trip.
How much time to set aside
One to two hours; with the overlook and Fairy Falls, half a day.
Best time
On sunny days, from late morning to mid-afternoon, when steam is usually lower and the colors show better. From May to October, when the road is open.
How to get there
By car, about 40 km from the west entrance and 15 km north of Old Faithful. The overlook is on the Fairy Falls trail, from its parking area.
Tip
Midway Basin parking lots fill up in mid-day during summer; arrive early or late afternoon. Hold onto hats: the wind often blows caps into the spring.
Official website
Get your questions answered
Frequently asked questions about Grand Prismatic Spring
Where is the Grand Prismatic viewpoint?
On the Fairy Falls trail, about 1 km from the trailhead parking lot, on a slope above the spring.
At what time of day are the colors of the Grand Prismatic most visible?
On sunny days, from late morning to mid-afternoon, when there is less steam over the water.
Can you enter the water of the Grand Prismatic?
No. The water is very hot and the ground around it is fragile; always stay on the boardwalks.