Bold claim: A decades-long silence ends as the world’s largest acidic geyser erupts again, right here in Yellowstone. And yes, this is exactly the kind of natural spectacle that captures our fascination and sparks questions about how these fiery wonders behave.
Here’s what happened: Echinus Geyser, a behemoth located in Yellowstone’s Norris Geyser Basin back area, has resumed activity after more than five years of dormancy. The feature sits roughly 66 feet across and is ringed by rock formations that resemble sea urchins. It earned its name from those spiky rocks, a nickname coined by mineralogist Albert Charles Peale during a visit in 1878.
What makes Echinus special is its chemistry. The geyser is acidic thanks to a mix of acidic gases and relatively neutral water. Unlike many acidic geysers that aggressively attack the surrounding rock, the acidity at Echinus isn’t strong enough to corrode the stones around it. The solution isn’t highly concentrated either, so think of it more like a less-aggressive orange juice or vinegar. That gentler chemistry leads to distinctive formations and colors, including the red hue around the pool and the spiny rock rims.
Historically, Echinus was a crowd-pleaser. In the latter half of the 20th century, viewing platforms and benches brought visitors closer than ever to the geyser. During the 1970s, eruptions occurred every 40–80 minutes; in the 1980s and 1990s, bursts could last up to about 90 minutes and reach heights of around 75 feet. Some days even featured horizontal eruptions that left warm spray soaking nearby onlookers.
Activity waned in the early 2000s. In 2010, researchers installed a temperature monitoring system in the geyser’s outflow channel, which helped track changes. The records show 15 sporadic eruptions between October 2010 and January 2011, with a long quiet spell lasting until October 2017. Then, a burst of consistency for several weeks followed by a sudden drop-off; the geyser largely quieted again, with only a few eruptions in the ensuing years.
February 2026 brought a revival. Echinus first showed signs of life on February 7, then erupted again over the following week. Beginning around February 16, regular eruptions reached about 20–30 feet every few hours.
More recently, scientists have observed bursts of activity that often precede eruptions, but the geyser’s actual eruptions have not always followed those precursors according to the temperature records. At present, the National Park Service cautions that it is unlikely Echinus will continue erupting through the summer, though nature can surprise us, and predictions aren’t guarantees.
If you’re curious to follow updates, see Yellowstone’s official notes and USGS temperature data for Echinus Geyser. This return to activity reminds us that even the planet’s most iconic landscapes retain an element of mystery and spontaneity.
Thought-provoking takeaway: What does a temporary resurgence of a major geyser tell us about the broader cycles of Yellowstone’s geothermal system—and how should visitors balance the thrill of witnessing a rare event with the need to protect these delicate environments? Share your thoughts in the comments: Do you believe such sporadic natural displays should be prioritized for public viewing, or should restrictions be tightened to safeguard these features for future generations?
