Yellowstone geyser erupts for first time in years

The Echinus Geyser—a Yellowstone National Park hot spring that periodically erupts and shoots hot water and steam into the air—has erupted for the first time since 2020.

The Echinus Geyser 

According to the U.S. Geological Survey’s Yellowstone Volcano Observatory (USGS YVO), Echinus is the largest known acidic geyser on Earth. 

It’s a rare type of geyser which has acidic waters, caused by a mix of acidic gases and neutral groundwater, within Yellowstone’s complex underground geochemistry. 

Michael Poland, a U.S. Geological Survey geophysicist and Scientist-in-Charge of the Yellowstone Volcano Observatory said it “sounds a bit scary, but the acid is not concentrated. Rather, it’s a bit like orange juice or vinegar.” It’s mildly acidic and not dangerously corrosive.

Echinus is surrounded by silica‑coated, spiny rocks that inspired its name after a mineralogist likened them to sea urchins in 1878. “Echinus” is a Latin scientific term associated with sea urchins and comes from the Greek word ekhînos, meaning “hedgehog” or “sea urchin.”

Echinus Geyser’s Eruption

USGS YVO said the eruptions began, for the first time in about five years, on February 7, followed by additional eruptions on February 9, 12 and 15, before shifting to eruptions every two to five hours starting February 16. 

The recent eruptions have lasted two to three minutes and reached approximately 20 to 30 feet. After each eruption, the pool’s water level drops sharply and typically takes about an hour to refill, mirroring behavior observed in late 2017. 

The activity happened in the Back Basin of Norris Geyser Basin, in Yellowstone National Park, roughly 660 feet from Steamboat Geyser, the world’s tallest active geyser.

Echinus’ pool is about 66 feet wide and is rimmed by a vivid red band of minerals which include iron, aluminum and arsenic. 

History of The Echinus Geyser

In the 1970s, Echinus erupted every 40 to 80 minutes, and in the 1980s and 1990s some eruptions lasted more than 90 minutes and blasted water up to about 75 feet, occasionally soaking onlookers, says the USGS YVO. 

A temperature monitoring system installed into the Geyser in 2010 has allowed scientists to track its surges and eruptions. Data shows that when water temperatures reach about 70°C eruptions are likely, while temperatures of around 40°C to 50°C are more commonly associated with surges—spurts of active water rather than full‑scale eruptions.

The geyser’s return provides scientists with fresh data on how geyser systems cycle between dormancy and activity and it also gives visitors a brief chance to see a feature that once erupted with near-clockwork regularity in the late 20th century.

What Happens Next

USGS YVO researchers say they don’t know how long the geyser’s eruptions will last, noting that there were no eruptions during the last few days of February—a pattern consistent with Echinus’s tendency to awaken for a month or two before going quiet. 

The USGS posted: “No increase in activity. Geysers are always turning on and off. That’s Yellowstone being Yellowstone!” on X, on March 2.

AccuWeather has urged visitors interested in seeing Echinus to stay on boardwalks, follow posted closures, and give thermal features plenty of space.