Yellowstone National Park, United States – Just before 9:23 a.m. MST on December 20, 2025, Black Diamond Pool in Biscuit Basin produced a dramatic hydrothermal eruption captured by the Yellowstone Volcano Observatory webcam.

This pool was the site of a major explosion on July 23, 2024, which destroyed a boardwalk and sent rocks and mud hundreds of feet into the air. Since then, dirty eruptions reaching 30 to 40 feet have occurred sporadically, keeping Biscuit Basin closed to visitors due to ongoing hazards.

Earlier this year, a new camera and seismic and acoustic monitoring station were installed, along with temperature sensors maintained by the Yellowstone National Park Geology Program. These instruments have improved detection and characterization of the pool’s eruptions, many of which were previously audible but not visible.

This morning, the eruption was clearly visible against bright blue skies and snow-covered surroundings, offering a rare and vivid view of the hydrothermal activity that has continued for the past 19 months.

The display highlights the unpredictable and powerful geothermal forces that define Yellowstone’s dynamic landscape.

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