Of all the stunning sights that Yellowstone National Park has to offer, by far and away the most majestic and awe-inspiring is the Grand Prismatic Spring. But what makes it so unique and what to expect when visiting the Grand Prismatic Spring in Yellowstone NP?
If you have any questions about visiting the Grand Prismatic Spring or the Midway Geyser Basin in Yellowstone, then this article is for you. In this post I share our experience visiting this awe-inspiring natural wonder and answer most frequently asked questions that we also had before our first visit.
What’s the cause of the mind-blowing colors of the Grand Prismatic Spring? Where is the Grand Prismatic Spring and what’s the best time to visit it? Can you visit the Grand Prismatic in winter? How to see the Grand Prismatic Spring from above?.. You can find the answers to these and many other questions in this ultimate guide to the Grand Prismatic Spring. Read on!
Featured image: Mitchell Rouse via iStock
Grand Prismatic Spring – Introduction
Grand Prismatic got its name during the Hayden Expedition, in 1871, but it was discovered earlier. First records date from the early European explorers and talk about a colorful spring. In 1839 fur trappers crossed the current Midway Geyser Basin area and noted a ‘boiling lake’. Both these mentions are believed to refer to what we now know as the Grand Prismatic Spring.
The 160 ft (almost 50m) deep Grand Prismatic is the largest hot spring in the United States and the third largest in the world. But it’s not just its incredible size that makes it so noteworthy.
The Spring’s stunning rainbow colors give it a surreal, other-worldly appearance, making it a must-see attraction and the highlight of any Yellowstone visit. Needless to say, Grand Prismatic is Yellowstone’s most photographed thermal feature and to many the main reason to visit America’s Oldest National Park.
Interesting Fact: Grand Prismatic Spring gets its name from the sequence of its colors, which conform to those of a rainbow, or the way a prism disperses sunlight! But more about the stunning colors below. Read on!
What makes the Grand Prismatic Spring so colorful?
Springs are formed when hot water emerges – unimpeded by mineral deposits – through cracks in the earth’s surface. This sets them apart from geysers, which erupt because the flow of water is obstructed at the surface.
The heated water initially rises, then falls, in an endless cycle. This produces extremely high temperatures (of up to 189 F – 87°C°) where the water bubbles up at the center, then cools as it spreads across the massive 370 ft (112m) diameter of the Grand Prismatic Spring.
The distinct ‘rings’ of temperature in the water contribute to the Grand Prismatic’s remarkable coloration, with different species of heat-loving bacteria (thermophile) inhabiting each zone. The type of pigmented bacteria thriving in these zones varies as temperatures change. This also means that the colors of the spring tend to change with the seasons, with the hues deepening in the summer months and fading in the winter.
The high temperatures at the center of the spring, however, make the water sterile, so it remains breathtaking blue all year round.
The almost perfectly horizontal orientation of the edges of the Grand Prismatic Spring and the area beyond them means that the water drains equally in all directions. This contributes to the uniquely stunning appearance of the spring, by creating the small, stair-like terraces at its edges.
Where is the Grand Prismatic Spring and how to visit the Midway Geyser Basin?
The Grand Prismatic Spring is the star attraction of the Midway Geyser Basin in Yellowstone. This basin may be small, but it’s home to some of the largest single springs in the world! Naturally, this area is extremely popular with tourists and it’s important to plan your visit ahead in order to avoid frustration. Especially if you are visiting in high season!
TIP: You should set aside 1 to 2 hours for your visit to the Grand Prismatic. More if you are planning to hike to the overlook.
As you enter Yellowstone National Park, look for signage to the Midway Geyser Basin. The Grand Prismatic parking lot is incredibly busy and priority seems to be given to the many visiting tour buses. Traffic can be heavy at times and is often impeded by visitors parking along the roads and around the parking lot entrance.
Expect to wait up to 20-30 minutes for a parking spot in the lot, especially after 10.30 AM in the summer, when the area is at its busiest.
While you can somewhat avoid the crowds if you visit early in the morning or late in the evening, it’s worth noting that the colors of the spring are at their most vivid in the middle of a sunny day. Further below you can read more about the best time to see the Grand Prismatic Spring.
Many people ask how long is the hike to the Grand Prismatic Spring? Grand Prismatic is just a few minutes walking distance from the car parking. It’s not even a hike – just a relatively flat walk on the wooden boardwalk. The boardwalk loops around the spring, allowing you to experience the warmth (and smells) of the Grand Prismatic right up close! The whole area is very wheelchair-accessible and also easy to negotiate with a stroller.
Our experience: We visited Yellowstone end of July, which is also the busiest season in the park. Despite the crowds, we chose to go to the Grand Prismatic in the middle of the day. Partially for the bright colors, but mostly because it just fit our itinerary best. It was busy at the Grand Prismatic car parking and we had to wait about 20 minutes for a free spot, but it wasn’t overly crowded on the boardwalks. It was a great experience and seeing the colors of the Grand Prismatic made us quickly forget the long wait at the car parking.
Other attractions of the Midway Geyser Basin
Whilst the Grand Prismatic is the main landmark of the Midway Geyser Basin, as you follow the boardwalks, you will also pass several other fascinating geothermal features of this unique area.
The Excelsior Geyser – now technically considered a hot spring – was most active before the 1900’s, when it would sometimes erupt nearly 300 ft (91m) high. It last erupted (to a less impressive height!) back in 1985 and has been dormant ever since. This steaming, vivid blue pool discharges over 4050 gallons (over 15,000 liters) of water every minute and has a temperature of 199 F (93°C).
Opal Pool is the smallest of the four major features of the Midway Geyser Basin. The colorful Opal Pool is considered to be a hot pool, but is actually a geyser. It erupts only a few times a year and has had some years of total dormancy. It has a temperature of 132 F (56°C). The Opal Pool owes its name to the gem-like clarity of its blue water.
The third largest spring (100ft – 30m) of the Midway Geyser Basin, Turquoise Pool is a hot spring with temperatures of 142-160 F (60-70°C). Place this beautiful blue spring anywhere else in the park and it will be a highlight in itself. However, its location just next to the impressive Grand Prismatic and the Excelsior Geyser, means that it’s overshadowed by its famous neighbors and therefore often overlooked.
The best time to visit the Grand Prismatic Spring
The most popular time to visit the Grand Prismatic Spring is between May and September, because these are the months during which the colors are the most vivid, beautiful and easy to appreciate. This is also the period when all the roads in Yellowstone are open and the time when most tourists visit this National Park.
On cooler or cloudy days – or when temperatures drop early in the morning or late in the evening – clouds of steam tend to form over the Grand Prismatic Spring. Whilst this steam can have a beauty of its own and often reflects the hues of the spring, some visitors find the view anti-climactic and are disappointed not to be able to view the rainbow brilliance of the Grand Prismatic in all its glory.
TIP: The best time to see the colors of the Grand Prismatic Spring is in the middle of a clear, sunny summer day. Just be prepared for the crowds!
READ ALSO: Top Tips for Visiting Yellowstone in Summer
Grand Prismatic Overlook – best way to see the spring from above
Because of the vastness of the Grand Prismatic, the best way to fully appreciate its beauty is to gain a little altitude and view it from above.
Until recent years, this was achieved (somewhat dangerously) by scrambling up a hill that branched off from the nearby Fairy Falls Trail. In the summer of 2017, the new Grand Prismatic Viewing Platform was opened to the public.
This overlook offers a unique vantage point of the Grand Prismatic and is the perfect place to see the spring as it looks in all the photographs that draw so many visitors to it each year… This is also the best place to take some memorable pictures of your own!
To reach the viewing platform, you need to get to the Fairy Falls parking lot, which is located 5 minutes drive to the south from the Midway Geyser Basin. From there, walk over the bridge across the Firehole River. The trail to the overlook platform is not particularly well sign-posted and is marked only with the word ‘Trail’. That being said, it’s quite easy to find by following the crowds headed in the same direction!
The trail starts as a wide gravel pathway and then forks a bit further down the road. The right fork takes you to the Fairy Falls, the left one takes you to the overlook. This part of the trail is steeper and the gravel can be quite loose and slippery, making the hike a little more challenging.
Most people in regular physical condition can manage this short climb quite easily, but it’s not a trail that can be done by people who have mobility issues. The outstanding views at the top are definitely worth the effort, so if you make just one hike in Yellowstone, make it this one!
Practical information: The Grand Prismatic Overlook trail is just a 1.2 mile (1.9 km) round trip, which ascends 105 ft (32 m). Depending on your level of fitness, it can take anything from 20 to 30 minutes there and back. You’ll probably spend more time at the overlook than walking to it.
Grand Prismatic Overlook is a relatively easy hike, but it’s still a hike. Make sure you wear good walking shoes, bring plenty of water, and don’t forget sun protection. Many people walk this trail in tennis shoes, but I suggest wearing light hiking shoes or even hiking boots because a part of the trail is quite steep, so you’ll need shoes with a good grip.
Can you visit Grand Prismatic in winter?
After September, the temperatures begin to drop quickly and Yellowstone prepares for the winter. Despite the less-vivid colors, visiting the Grand Prismatic in autumn can be a really rewarding experience. You will find the stunning autumn colors of the surrounding landscape, fewer people, and the chances of spotting wildlife at the Grand Prismatic are also bigger.
Although this depends a bit on the weather each year, usually the roads in this part of the park remain open through late October. Visiting the Grand Prismatic Spring in the winter is not possible on your own, since the roads are closed to all private vehicles. However, it can be done with a guided tour.
There are several park-authorized companies that run winter tours to Yellowstone. You guessed it right – the best way to visit Yellowstone in winter is by snowmobile or snowcoach. Here you can book Yellowstone snowmobile tour and here – Yellowstone snowcoach tour (both start from Jackson Hole or Teton Village).
I wasn’t successful in finding a tour that clearly states that they also visit the Grand Prismatic Spring in winter; most seem to stop at the Old Faithful, but don’t go further north. Yet, I’m sure it is possible because there are some people who say they did it. So if you really want to see the Grand Prismatic Spring in winter, you’ll have to research a bit more for local tour operators who go to that part of Yellowstone by snowmobile.
People who have braved the elements and visited Yellowstone in winter, say that it’s an unforgettable experience. Not even to mention all the fun of driving the snowmobile or getting to see the bison in the snow…
TIP: If you want to visit Yellowstone in winter, but are not sure where to start, you may want to check this 5-day Yellowstone winter wildlife tour that starts and ends in Bozeman. It’s a great tour for those who want to see wildlife, especially wolves.
Safety at the Grand Prismatic Spring
This area of outstanding natural beauty is not without its dangers and over the years there have been at least 20 people killed by its thermal features. Don’t let this scare you though – visiting Grand Prismatic Spring is perfectly safe and there is nothing to worry about, as long as you follow the signs and don’t do any stupid things.
The boardwalks at the Grand Prismatic are not just a convenient viewing platform; they also offer protection from the hazards of the local terrain. Many deaths and severe injuries have been caused by visitors going ‘off trail’ and stepping through the thin crust of the earth into the boiling waters below.
There are hardly any railings alongside the boardwalks at the Grand Prismatic, so you may want to hold on to your kids’ hands.
Even if you feel tempted to ‘test the waters’ by putting in a finger to see how hot they are, please don’t! Yellowstone Rangers believe that the number of injuries at the geothermal springs are higher than recorded since many people are too embarrassed to admit to burns caused by dipping their fingers into thermal pools.
There is abundant wildlife in the area, including untamed bison and bears. It’s not very likely you’ll see lots of wildlife during the busiest hours of the day. However, if you do see any wildlife, remember to keep a safe distance at all times.
Dogs are not allowed in this area at all.
Can you swim in the Grand Prismatic Spring?
It is illegal to swim, bathe or wade in the thermal features of the Grand Prismatic Spring. You could get burned or it can even be fatal!
If you want to go swimming in Yellowstone, you should know that it is only allowed in a few designated areas, namely Boiling River and the Firehole swim area. There are no lifeguards and swimming is always at your own risk. Thermal waters can also contain organisms that can cause dangerous infections and rashes, so experts recommend that you never swallow water from the rivers or fully submerge your head.
That being said, we went swimming at the Boiling River and it was one of the best experiences in Yellowstone!
READ MORE: Boiling River of Yellowstone
Protecting the environment
Going ‘off trail’ in order to take the perfect photograph of the Grand Prismatic is not just dangerous, it can also upset the fragile ecological environment.
Be mindful of preserving the natural wonders by staying in the designated areas and ensuring that no foreign objects enter the thermal waters. Sun hats are a big problem because it’s often very windy at the Midway Geyser Basin. We saw so many hats lying around and polluting the natural features in this area, it’s really sad.
Please note that the use of drones is not allowed at the Grand Prismatic Spring.
Facilities at the Midway Geyser Basin
There are bathroom facilities at the Grand Prismatic parking lot. However, coach-loads of people here might lead to really long waiting times…
There are many drinking-water stations all across Yellowstone, but I can’t recall if there is one at the Grand Prismatic. In any case, it’s always wise to bring plenty of drinking water with you. Make sure to pack a reusable water bottle – you’ll be able to refill it at many locations in Yellowstone. Good for the environment and for your wallet.
There is no shade in the Midway Geyser Basin, so sun protection is a must in summer.
TIP: There is a picnic area – with parking – 1/4 mile north of the Grand Prismatic Spring – Whiskey Flat Picnic Ground. It has nice clean restrooms and no crowds.
So, this is our guide to visiting the Grand Prismatic Spring in Yellowstone. I hope it answers all your questions. If you have a question, please leave a reply below and I’ll try to help.
If you found this guide useful, make sure to also check our guide for visiting the Old Faithful Geyser and also our guide to the Upper Geyser Basin and Mammoth Hot Springs other must-sees in Yellowstone National Park.
TIP: For more information about visiting Yellowstone, please also check the following detailed guides on our website.
- Best things to do in Yellowstone
- 1 day in Yellowstone
- 2 days in Yellowstone
- Yellowstone Itinerary
- Where to stay in and near Yellowstone
- When to visit Yellowstone + tips for each season
- Yellowstone with kids
- What to pack for Yellowstone
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