Geologists Say a New Hole Has Appeared in Yellowstone National Park
A sleeping giant lies under the park. Could this be a sign that it's stirring?
Published July 23 2025, 4:06 p.m. ET
Geologists working in Yellowstone National Park were treated to a surprise in April 2025, when they discovered a blue hole in one of the basins. The hole was discovered during a routine inspection, which involves testing the temperatures in the logging stations around the basin.
The news may be concerning to some, since Yellowstone's park is known to sit above an extensive volcano system known as a supervolcano.
This has prompted speculation that the new hole in Yellowstone is a sign of underground activity, which has left some looking for more information about what exactly is happening at Yellowstone.
Fortunately, it seems like the experts have a pretty good idea of what caused the new pool to form, and they think they can even pinpoint when it happened as well. Keep reading to learn more.
A new hole has been discovered in Yellowstone.
On July 14, 2025. The U.S. Geological Survey (USGS) posted the news that geologists had found a "new thermal feature" during routine inspections. The pool was discovered in a subbasin of the Norris Geyser Basin, in an area known as Porcelain Basin.
The new pool is west of Tree Island, which is a wooded area of vegetation near the logging station.
The new pool is approximately 13 feet across, and the water measured roughly one foot deep. According to the USGS, the temperature was a balmy 109 degrees Fahrenheit within the new pool, and it appeared to be a shade of light blue.
Several small rocks surrounded the pool, and they were all covered in a fine sandy mud.
What caused the new pool to appear in Yellowstone?
Based in evidence collected at the scene, ongoing observations in the area, and satellite imagery, the geologists believe that the pool was caused by a hydrothermal explosion, which was then filled by an underground spring.
The USGS defines a hydrothermal explosion as one eruption that takes place when water from a volcano's hot water system gets super-heated, flashing to steam, and breaking up rocks and Earth in the process.
While this may sound like a scary and violent occurrence, it's not a rare one in this area of the park. The USGS says that there have been a number of these events in the region, including some that were witnessed while they were happening, like Porkchop Geyser's 1989 explosion.
Unfortunately, since the new blue pool at Yellowstone wasn't heavily observed as it was forming, geologists are still trying to piece together a picture of what caused the explosion to happen in the first place.
It sounds like they have been able to conclude that the new feature wasn't formed at once in a single large event, but instead it may have grown to be thanks to a series of small events that they believe began on Dec. 25, 2024.
Whether they change their theories after reviewing all of the data they've collected from the area remains to be seen, but for now it seems like they've ruled out earthquake swarms as a source of the activity.
That's something that should ease the minds of anyone in the region who worries that this new pool is a sign that the supervolcano beneath Yellowstone is getting ready to erupt.