Along with Old Faithful and the Grand Canyon of the Yellowstone, one of the things you MUST see in Yellowstone is the Grand Prismatic Spring. In this article, I’ll cover everything you need to know about it.
What is the Grand Prismatic Spring?
The Grand Prismatic Spring is the largest hot spring in Yellowstone and the third largest in the world. It is over 300 feet long, 200 feet wide, and 100 feet deep. It gets its name from the colorful edges — resembling a light prism — with blue, green, yellow, orange, and red color rings.
Grand Prismatic is a Hot Spring
The Grand Prismatic is a hot spring.
In Yellowstone, there are five kinds of geothermal features: hot springs, geysers, fumaroles, mud pots, and travertine terraces. They are all closely related — mostly having to do with water being heated underground and working its way to the surface.
The big difference between a hot spring and a geyser is the plumbing. Geysers have a constriction, or a bottleneck, causing the water to get trapped, build pressure, and explode!
Hot springs don’t have the constriction. So hot water rises to the top, cools, and returns to the bottom. The water circulates freely.
Some hot springs used to be geysers, but something happened to alter the constriction, like an earthquake or a massive eruption.
Grand Prismatic is BIG
There are only two bigger hot springs in the world: Frying Pan Lake in New Zealand and Boiling Lake in Dominica. The Grand Prismatic is 370 feet in diameter and over 120 feet deep.
At Yellowstone, it’s common to walk around on boardwalks and look down into deep blue hot springs. There are several gorgeous springs.
Grand Prismatic is a little different because you can’t get close enough to look down into it. Rather, it’s more like you’re looking out over a steaming pond or mountain lake. In fact, in the early days, it was also called Prismatic Lake or Emerald Lake.
For that reason, some people don’t seem too impressed by it. It is hard to take it all in. It’s why you need to see it from next to the spring and from above (see below).
Grand Prismatic is Colorful
It’s named Prismatic because it has the colors of a light prism. The colors are actually millions of tiny organisms called thermophiles (“thermo” = heat; “phile” = lover).
These organisms can ONLY live in hot temperatures — until it gets too hot even for them. The temperature will determine which organisms can survive, and therefore what colors we see.
The center of the hot spring is a deep blue — it’s too hot for any organisms to survive. As the water moves towards the edges and flows out of the hot spring, it cools, changing the colors from green to yellow to orange to red to brown.
When you see it from a higher viewpoint, it looks like a big eye. Almost like Sauron in Lord of the Rings — but not as spooky. It’s the one hot spring to rule them all!
How to See Grand Prismatic Spring
There are two ways to see it: next to it and from above.
Next to it
It has its own parking lot: the Grand Prismatic Spring parking lot. You’ll walk on the bridge crossing the Firehole River and continue on the boardwalk.
It makes a loop around the Midway Geyser Basin and continues along the edge of the Grand Prismatic for a while.
To see it from above you need to park at the Fairy Falls parking lot. Take the Fairy Falls hike.
The Fairy Falls hike is about 5.5 miles round trip, but you only need to walk the first .5 miles before turning left to the Grand Prismatic Spring Overlook. Walk another .3 miles and you’ll arrive at a viewing station.
This viewpoint has exploded in popularity lately. In fact, it wasn’t even an official viewpoint until 2017.
If you would like a step-by-step guide for seeing Grand Prismatic, as well as the rest of Yellowstone, check out our Yellowstone Itinerary & Audio Guide.
Where is Grand Prismatic Located?
It’s located in the Midway Geyser Basin. This is located between Madison Junction and Old Faithful.
This general area of the park is composed of (from North to South): Lower Geyser Basin, Midway Geyser Basin, and Upper Geyser Basin.
Notice they are named after their elevation, not their direction. So Upper Geyser Basin (which contains Old Faithful) is the lowest on the map.
Midway is the smallest of the basins. It contains:
- Grand Prismatic. Obviously the star of the basin.
- Excelsior Geyser. This is almost as large as Grand Prismatic. See below.
- Opal Pool & Turquoise Pool. Nice hot springs in their own right. They suffer from a comparison problem. It’s hard to stand out in your neighborhood when your neighbors have mansions.
Don’t Even Think About Flying a Drone Over Grand Prismatic!
Like Florida Man, Yellowstone Visitor is always up to something bizarre.
In 2014, the National Park Service banned drones from all national parks. Just two months later, a tourist from the Netherlands crashed his drone into the Grand Prismatic Spring.
The park service was very concerned it could damage the colors of the spring, something that happened to Morning Glory spring after people threw debris in it over the years.
The park service looked at all sorts of options to retrieve the drone but to no avail. The drone still sits at the bottom. The tourist was fined over $3,000.
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Don’t Forget About Excelsior Geyser
Imagine the huge Grand Prismatic as a geyser — that’s basically what the nearby Excelsior Geyser used to be.
It’s almost the size of Grand Prismatic, and it used to erupt in massive explosions that were 300 feet wide and 300 feet tall! Imagine!
This geyser became famous after the park was created in the late 1800s, as the explosions were unlike anything ever seen.
Unfortunately, the geyser eruptions slowed down, and they became dormant by 1900. Since it really isn’t a geyser anymore, it’s called Excelsior Geyser Crater.
Remarkably, there is one known photo of this geyser erupting. In 1888, park photographer Frank Jay Haynes snapped a photo of this event.
Visiting Yellowstone and Need a Game Plan?
Yellowstone is a big and complicated place to see. I simplify it in my itinerary/guide so you don’t have to do a ton of research.
I’ve been visiting Yellowstone for over 30 years and I’ve even I’ve had many frustrating trips because the park is so big. If you don’t have a plan, you’ll wander around inefficiently.
Use my guide and LOVE your trip to Yellowstone.
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