Yellowstone National Park is home to a huge collection of bubbling geologic cauldrons, one of which boiled a bison alive in front of tourists earlier this month. Geologists figured they had every hot spring mapped out, only for a brand-new one to suddenly appear out of nowhere.This past April, geologists stumbled on a shimmering 13-foot-wide blue thermal pool in the park’s Norris Geyser Basin. Weird. It wasn’t there a few months earlier.Discovered during routine maintenance, the pool sits in the Porcelain Basin subarea. It’s 109°F water now calmly rests a foot below the rim, surrounded by light-gray, mud-covered rocks. The U.S. Geological Survey suspects the pool is the result of a hydrothermal explosion, a kind of underground steam burp where pressurized water suddenly vaporizes and blows out debris. Luckily, no one was around to see it happen; otherwise, they would have been bombarded with some very hot water and chunks of Earth.the mysterious blue pool. Photo: U.S. Geological Survey / Mike PolandWhile the pool wasn’t discovered until April 2025, geologists suspect it was formed sometime between December 2024 and February 2025, somehow leaving no trace of the “series of mildly explosive events” that likely created it. Instead, newly installed infrasound monitors picked up a weak, low-frequency acoustic blip on three different dates with no big seismic activity to match.Satellite imagery backs up the story. There was nothing on December 19, a small depression in early January, and a full pool by February. Geologists now think the feature formed from several small hydrothermal burps rather than one big blowout, which flung rocks and silica mud aside just enough for silica-rich water to fill the void and create a serene blue pond, officially kicking off the countdown until it becomes an Instagram hotspot.The post A Mysterious Blue Pool Just Appeared in Yellowstone National Park appeared first on VICE.