Get to know Grand Geyser

Do you have what it takes to see the tallest predicted geyser in the world? Not everyone does, but this article will let you know what to look for while waiting for Grand Geyser.


Grand Geyser is the tallest predicted geyser in the world with many eruptions reaching about 200 feet. Most people would agree that it’s better than Old Faithful. Not only does it last about seven minutes longer than Old Faithful, but it’s wider and taller than Old Faithful. But it takes more patience to see an eruption as it’s window of opportunity to erupt (prediction) is wider than Old Faithful’s. It’s around 2 hours (or more depending on Grand’s current cycles) as opposed to 20-25 minutes for Old Faithful.


Grand Geyser eruptions have changed over the years. Before the 1969 Hebgen Lake Earthquake, the eruptions would come in consecutive bursts. As Park Naturalist, George Marler wrote in his

“During an active phase Grand had several independent eruptions, most of which lasted scarcely more than a minute. Following each separate explosion, the water column dropped with a suddenness that almost equaled its explosive ejection. Much of the falling water rushed back into the crater, but immediately there was doming and another explosion.”

These eruptions lasted 12-20 minutes and consisted of an average of 8 to 12 bursts. However, he reported at times some eruptions lasted up to an hour with 30 or more bursts. He said the second to fifth bursts were the tallest. How fun that must have been to watch!

Now the eruptions commonly have one or two bursts or up to rare 6 or 7 bursts. The eruptions last 10-12 minutes. If there’s a second (or third, or more) burst, they can be much taller than the first. As I understand, that’s because the weight of the water is less in the plumbing system and yet the intense thermal energy is still there.



Grand Geyser is located in the Upper Geyser Basin, just a short walk from Old Faithful. Start walking “down basin” toward Castle Geyser along the bike path (the old road to Old Faithful) and turn right onto the boardwalk by Castle Geyser. Keep walking along this path until you reach the area of benches.

You can also reach Grand Geyser from Geyser Hill. As you walk around the loop there, there’s a boardwalk path near Lion Geyser that will take you over to Grand.

When you reach this area, know that the raised rim is not Grand Geyser. That’s Turban Geyser. Grand erupts from the pool in front of and next to Turban. There’s also a third geyser here – Vent Geyser. Vent is difficult to see until it starts to erupt after Grand has started.



There are a few keys to watching Grand Geyser:

• Turban Geyser
• Water level in the pool of Grand
• Amount of overflow from Grand
• Geyser Gazers
• Other geysers in the area

Turban Geyser
Turban Geyser erupts about every 20 minutes. This is an opportunity for Grand to erupt. While either Grand or Turban might start first at the main event, the minutes leading up to the next time when Turban is due to erupt is when to pay attention to what’s happening at Grand’s pool. The fact that Turban erupts every 20 minutes helps you to wait a bit longer. You just have to decide how long you’ll give it. Is it worth the wait? Everyone that does wait says, “YES!”

Water level
Grand’s pool rises and falls a couple of inches, exposing and covering some rocks you’ll see out there in the pool. What you hope for is high water levels that cover these rocks and stronger overflow with slightly more steam. When things look “really good” you’ll see small waves breaking over the rocks that are covered. While this isn’t a guarantee that Grand will erupt on this cycle, it’s a likelihood.

Geyser Gazers
Geyser enthusiasts (known as geyser gazers) often gather about in the middle of the benches surrounding Grand Geyser. If things are looking good, they’ll stand to get a slightly better view.

Other Geysers
Sometimes other connected Geysers to Grand can delay an eruption of Grand Geyser. Vent Geyser occasionally starts to overflow that can cause a delay. And sometimes Rift Geyser seems to affect the length of time until an eruption of Grand. So, while Grand is often fairly predictable, there are occasional eruptions that take much longer to happen than most. It keeps us guessing.


The eruption will start with a slight blip of water breaking the surface. Occasionally it will dome into a “blue bubble” moments before the water column rockets skyward. The height of this first burst is held for 10-15 seconds before it begins to slowly descend where it will continue until enough water is lifted from the system. Then tall, quick spikes will begin to show themselves.

A minute or so after Grand starts, Vent Geyser, joins in on the fun. Vent Geyser reaches about 70 feet and would be a star of its own if it weren’t overshadowed by Grand.

At about 8 minutes in, you might see the eruption calm down completely. This is a good sign. That means there will likely be a second burst. This burst is usually taller than the first. If it dies down as well and you still see water in the crater, stay for a bit longer as there might be a third burst.

The general rule is to never leave Grand until you see the water drain from the crater. If there’s water, there’s always a chance for another eruption.


Grand Geyser has been a favorite of many for decades, but many fewer people make the time in their vacation schedule to head down and watch this darling of a geyser. It does take more of a time commitment but is a delight. I often hear people describe it as a type of fireworks – but of water. If you want to do something a bit out of the ordinary, catch Old Faithful, yes, but go and catch Grand.


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