Yellowstone's Echinus Geyser Resumes Activity

The world's largest acidic geyser, Echinus Geyser in Yellowstone National Park, has recommenced eruptions after more than five years of dormancy. The national park announced the renewed activity recently.

Geyser Characteristics and History

Echinus Geyser is situated in the back basin of the Norris Geyser Basin and measures approximately 66 feet in width. Its naming in 1878 by mineralogist Albert Charles Peale was prompted by the surrounding rocks, which he observed to resemble sea urchins.

The geyser's acidic nature stems from a combination of acidic gases and neutral waters. However, its acidity level is not sufficient to corrode the surrounding rock, being comparable to substances like orange juice or vinegar. This unique water chemistry contributes to distinct formations and a red coloration around the geyser pool.

During the latter half of the 20th century, Echinus Geyser erupted frequently. In the 1970s, eruptions occurred every 40 to 80 minutes. By the 1980s and 1990s, eruptions could extend up to 90 minutes and reach heights of 75 feet, occasionally projecting horizontally.

Recent Activity and Monitoring

Echinus Geyser's activity began to decline in the early 2000s. A temperature monitoring system installed in its outflow channel in 2010 recorded 15 sporadic eruptions between October 2010 and January 2011. Eruptions remained infrequent until October 2017, when consistent activity was observed for several weeks before abruptly ceasing. Subsequent years saw minimal eruptions.

In February 2026, the geyser exhibited signs of renewed activity, with an initial eruption on February 7, followed by more throughout the subsequent week. Regular eruptions, reaching 20-30 feet, commenced every few hours starting February 16. Recent data indicates spikes in activity that typically precede eruptions, though no actual eruptions have occurred in the most recent days.

Future Outlook

Yellowstone National Park officials state that it is improbable the geyser's current eruption cycle will persist into the summer season, though definitive predictions are not possible.