Upper Geyser Basin in Yellowstone National Park has the highest concentration of geysers anywhere in the world. This section of the UNESCO World Heritage-listed park is often overlooked because many people concentrate on Old Faithful, but it’s definitely worth walking through. There are a good number of geyser groups in the basin making for a good few miles of walking. This entry focuses on Grand and Castle Group and describes only a few of the geysers and pools in the area.
The Grand and Castle Group can be accessed by the boardwalk near Goggles Spring on Geyser Hill. The walk starts near the Firehole River and continues to the geysers. There are a lot of geysers and springs to see in this group. Many of them are entertaining to watch.
The first geyser I saw was Tardy Geyser. It can shoot water 20 feet into the air. Eruptions occur within minutes or several hours.
Next was Sawmill Geyser. This was a fun geyser to watch as it shot water out in spurts and gave everyone on the boardwalk a nice shower. It erupts every one to three hours with eruptions lasting anywhere between a few minutes and a few hours. Water can shoot up to 40 feet into the air. It’s named after the grinding sound it makes as it erupts, similar to a sawmill in action. When the eruptions finish, the water drains and it looks like an empty crater.
At Sawmill Geyser, there is a four-way intersection. I turned to the right and headed to Spasmodic Geyser, which was my favorite geyser in Upper Geyser Basin. It’s made of two main vents and many smaller vents. As the name suggests, it has irregular eruptions. They last anywhere from 10 minutes to several hours with one to three hours between eruptions. It can shoot water 15 feet into the air from either of the main vents.
I continued with Oval Spring, which is at the intersection of the boardwalk. It’s usually calm but has erupted at least once in the past century.
West Triplet Geyser
West Triplet Geyser is one of three geysers located very near to each other. It looks like a dry white ring but actually erupts once or twice a day. Before 1947, it erupted roughly every three hours.
Nearby is Grand Geyser, which happens to be the tallest predictable geyser in the world. Water from its 30 foot wide pool reaches heights of up to 200 feet with eruptions occurring every six to 15 hours. Grand Geyser is boring to look at when it’s inactive and it’s pretty far from the boardwalk. It’s connected to two smaller geysers, Turban Geyser and Vent Geyser, which erupt every 15 to 30 minutes at heights of ten feet and 70 feet respectively.
Economic Geyser and East Economic Geyser are next. They’ve been mostly inactive since the 1920s but used to be popular geysers for tourists. They’re named “economic” because when they erupted, the water they ejected drained right back into the vent, thus appearing to “save” water. One interesting fact is that their colors often change due to changes in water temperature. When the water is cooler, the colors are darker because they attract different types of algae and microbes. When the water is near boiling, they’re filled with clear water. At the end of the geyser group, before continuing to the Giant Group, is Wave Spring, which is a calm pool with red colored water.
Moving back to Sawmill Geyser, if you turn left at the intersection and walk past a few features you’ll come to Crested Pool. It’s one of the more beautiful pools in the Upper Geyser Basin and also one of the largest and hottest. It’s nearly 30 feet across and 42 feet deep. Crested Pool is in a constant state of boiling. At the bottom, temperatures at 237°F have been recorded. In 1970, a young boy was killed when he ran into the steam and then into the spring.
The huge cone nearby is Castle Geyser, which resembles the ruins of an old castle. It erupts every 10 to 12 hours with water reaching heights of 60 to 90 feet. Eruptions normally consist of a 20 minute water phase followed by a 40 minute steam phase. Castle Geyser is very old. Its cone, about 12 feet high, is estimated to be anywhere between 5,000 and 15,000 years old.
Across the path is Shield Spring. It’s a calm pool about 12 feet across. A large vent with a bunch of smaller vents that make up the pool.