When people think of Yellowstone, the first thing that often pops up in their head is Old Faithful. Now while Old Faithful is an awesome feature and a big reason for why this park gained popularity, there are so many more cool features beyond it. Yellowstone has several different thermal areas throughout the park. the largest concentration of geysers in the world is in the Upper Geyser basin. Behind Old Faithful there is about 3 miles of boardwalk that takes you through different Geysers, Hot Springs, and Fumaroles. 

Thermal features a created from magma beneath Earth’s surface heating up groundwater. The groundwater rises through cracks in the earth until it reaches the surface in the form of hot springs, fumaroles, mudpots, and geysers. Often thermal features share the same plumbing — the cracks in which the groundwater travels — leaving them to “fight” over where the water goes. The plumbing is also subject to change due to earthquakes or water supply. This uncertainty of where the water will be building and how long it will take to reach the amount needed for an eruption makes it very difficult to predict when an eruption might occur. In order for a geyser to be predictable in needs to have a constant water source, meaning they are often not connected to other thermal features that could steal that source. Due to this predictable geysers are in the minority, making the Upper Geyser Basin a unique area as there are 5 located there. While these geysers are considered predictable they still often have a window in time in which they can erupt. For instance Old Faithful might have an eruption time of 5:00, but it can often go off anywhere from 13 minutes before or 13 minutes after (and this is not even exact as I have seen Old Faithful go off 30 minutes early and late).

Old Faithful

The 1870 Washburn Expedition “discovered” Old Faithful, they were so impressed with its regularity that they gave it its namesake. Prior to the 1959 Hebgen Earthquake it erupted on average every 64 minutes. Since then the interval has been slowly increasing and is now around 90 minutes. Studies on the geyser on still on-going, they recently found another underground chamber that seems to be related to geyser in 2015.

Grand Geyser

This is one of the most spectacular geysers in the Upper Geyser Basin. It is the tallest fountain geyser in the world. A fountain geyser erupts out of a pool instead of cone, like Old Faithful. This geyser erupts in multiple bursts, the first always being the shortest at around 100 feet tall. Occasionally it will be followed by a second burst that can reach up to 200 feet. 

Riverside Geyser

Riverside is located right along the Firehole river, hence its name. A few hours before an eruption the cone will start to overflow into the river. Riverside is one of the most regular geysers in the park and can be predicted relatively close to its actual eruption time. Riverside’s interval has stayed pretty stable since its discovery in the 1880s. 

Castle Geyser

Castle earned its name from the “castle-like” cone shape. The cone is 12 feet and lets us know that there were periods of dormancy for Castle geyser, as several trees were able to grow on the location of the cone. Once Castle was active again the geyser killed and eventually covered those trees in geyserite. Castle has a water phase for roughly 20 minutes, spraying water 75 feet up in the air.

Daisy Geyser

Daisy Geyser erupts more frequently than most predictable geysers and is sometimes more predictable than Old Faithful. Daisy is a fountain geyser that can reach a height of 75 feet. Prior to 2001 Daisy used to be more predictable than Old Faithful with an interval from 85 to 110 minutes. 

Giantess Geyser

Giantess is a pretty rare geyser to witness. On average it goes off 2 to 3 times a year, but it has been relatively inactive the last few years. The last recorded eruption of Giantess was my first summer out here on August 10, 2021. Giantess is a fountain geyser that has an active phase lasting up to 43 hours. During the active phase it has periods of dormancy and eruptions reaching 200 feet. 

Lion Group

There are 7 different geysers that make up the Lion group, four cone geysers and three fountain geysers. Lion is the largest geyser in the group and is considered a cyclical geyser. It has an initial major eruption that can reach up to 70 feet for 6 minutes. Following that first eruption there will normally be a few eruptions every hour and a half that are not as tall and do not last as long. On average the cycle will consist of two to four eruptions. 

Beehive Geyser

The average interval between eruptions for Beehive is 16 to 20 hours. Occasionally it will have an interval as short as 8 hours or as long as 24 hours. Prior to 1970 its eruptions would happen every few days or even weeks. Beehive is a cone geyser; water erupts 150 to 200 feet from the four foot tall cone. Sitting right next to Beehive is a vent, which is referred to as Beehive’s Indicator. Typically the indicator will erupt about 10 to 15 minutes before Beehive erupts. The indicator is used as a signal to alert people that Beehive will most likely be erupting soon, although this is not 100% accurate. 

Solitary Geyser

In 1914 Henry Brothers was allowed to build a heated swimming pool in the Upper Geyser Basin by draining water from Solitary. After the water level was lowered from the swimming pool Solitary started having eruptions. Even after the swimming pool was removed in 1951 and the drainage area was fixed, Solitary has continued having eruptions. Solitary Geyser is one of the many examples in the park on how our actions can have drastic effects on the delicate features here. 

Giant Geyser

Giant Geyser is the tallest geyser in the Upper Geyser basin, but is not predictable. Giant is a part of the Giant group, which undergoes frequent “hot periods”. Although Giant does not erupt during every hot period, it is only during hot periods that it does erupt. A hot periods consists of Bijou geyser becoming dormant, Feather erupting, and there are small jets of water coming out of Giant’s cone. When Giant does erupt it can be anywhere from 200 to 250 feet tall. 

Grotto Geyser

Grotto Geyser gets its unique cone from trees that once grew in that area and were eventually covered in geyserite. Most of Grotto’s eruptions last an hour to 3 and half others, followed by an interval of 5 to 8 hours. Occasionally Grotto will have marathon eruptions which last as long as 12 hours. At the beginning of eruptions the height of eruptions can reach 40 feet, but quickly lower to around 15 feet. There is a connection between Grotto Geyser and Giant. Sometimes after a marathon eruption Giant will erupt, due to a recovery hot period in the Giant group. 

Morning Glory Pool 

The original road into the Upper Geyser basin passed right by Morning Glory making it one of the most popular thermal features in the park. Morning Glory has had one recorded eruption, which happened in 1944. Unfortunately due to people throwing objects into the pool it’s temperature, and therefore color, have dulled over time. In 1950, park service induced an eruption from the pool to clear out some of the debris. There was $86.27 in pennies alone from that eruption. 

Artemisia

Artemisia gets its name due to the similar color of geyserite formations surrounding the pool to sagebrush. Before an eruption the water level rises leading to significant overflow and is followed by thumping in the cavity beneath the ground. When Artemisia has eruptions it can reach 30 feet lasting for 15 to 30 minutes. After eruptions the water level in the pool is lower and takes several hours to refill.

Punch Bowl Spring

Punchbowl is a hot springs located on a trail far left of the bike trail. This hot spring has a wall of geyserite surrounding it, giving it a “punchbowl” look. It is constantly bubbling as it sits right at the boiling point for this elevation: 198 degrees Fahrenheit. In the 1910s-1920s water from Punch Bowl Spring was piped to the kitchen for the Wylie Campground, located on a hill near the spring.