Mysterious boiling hole suddenly appears in Yellowstone National Park

A new boiling pool the size of a small swimming pool has unexpectedly appeared in the Biscuit Basin area of Yellowstone National Park, just two days after scientists from the U.S. Geological Survey had walked across the very same site. The event marks the second hydrothermal explosion in Biscuit Basin in the past two years.

According to ScienceAlert, sensors recorded seismic activity and a low-frequency acoustic signal, or infrasound, from the Biscuit Basin at 6:09 a.m. Mountain Time on June 13. At the same moment, a camera operated by the Yellowstone Volcano Observatory captured dark steam rising north of Black Diamond Pool, matching the anomalies detected by monitoring instruments.

The following day, geologists discovered three new hydrothermal vents. Pressurised hot water had forced its way to the surface and rapidly turned to steam, triggering an explosion. By the time scientists inspected the site, the water had cooled to about 85°C, but rocks ejected during the event were scattered along a fracture measuring 18.5 metres in length and up to 1.5 metres in width.

When researchers returned on June 16, they found an actively boiling pool measuring 6.5 by 5.3 metres, producing distinctive muffled thumping sounds as steam bubbles formed and collapsed beneath the surface. The absence of surrounding debris led scientists to conclude that the pool had formed through ground collapse rather than an explosion, explaining why it had not been captured by surveillance cameras.

On June 18, cameras recorded intermittent water jets rising 6 to 9 metres behind the new pool. Scientists say the event is particularly significant because, of all the hydrothermal explosions documented in Yellowstone, this one occurred closest to the park's monitoring network, offering a rare opportunity to determine whether any warning signs preceded the event.

The previous hydrothermal explosion in Biscuit Basin, in July 2024, hurled scorching rocks into the air and severely damaged tourist boardwalks. No injuries were reported in the latest incident.