Echinus Geyser Erupts Repeatedly in Yellowstone

Echinus Geyser, the world's largest acidic geyser, has erupted repeatedly in Yellowstone National Park's Norris Geyser Basin for the first time since December 2020, drawing attention to one of the park's rare hydrothermal features. The activity began on February 7, 2026, in the Back Basin area, with subsequent eruptions occurring every two to five hours starting February 16.

According to the U.S. Geological Survey, the geyser's resurgence started with signs of frothing in early February, followed by the initial blast on February 7 and additional ones on February 9, 12, and 15. Each eruption lasts two to three minutes, propelling acidic water up to 30 feet into the air and causing the geyser's 66-foot-wide pool to drop sharply before refilling over about an hour. The water reaches temperatures around 158 degrees Fahrenheit during these events, mirroring patterns observed in a brief active period in late 2017.

Echinus stands out due to its acidic chemistry, with a pH similar to orange juice or vinegar, resulting from a mix of acidic gases and neutral groundwater. This balance prevents the erosion that typically dooms acidic geysers, as the acidity is mild enough not to corrode the...