Yellowstone Biscuit Basin to be closed for summer after hydrothermal explosion

An area of Yellowstone National Park in Wyoming will be closed the rest of the 2024 season after a hydrothermal explosion launched debris and destroyed a nearby boardwalk.

The National Park Service said Thursday the Biscuit Basin, which is a few miles north of Old Faithful, will be closed for the remainder of the summer following the explosion near the Sapphire Pool.

Small explosions could be possible in the coming days and months, though the Grand Loop Road — which surrounds Biscuit Basin and other popular sites — will remain open to vehicles, the agency noted.

“Hydrothermal explosions typically occur in the park one to a few times per year, but often in the back country where they may not be immediately detected,” the park service stated.

No injuries were reported in the explosion, according to officials.

Videos quickly circulated social media showing the explosion scatter gray and black debris into the air and toward the nearby boardwalk. Visitors are then seen quickly walking away from the explosion as smoke billowed into the sky and steam rose from the water.

Pictures later released by the park service showed the heavily damaged boardwalk near Biscuit Basin, which was hit by “grapefruit-sized rocks.” Some of the debris were about 3 feet wide and weighed hundreds of pounds, the park service said.

The hydrothermal explosion was due to “water suddenly transitioning to steam in the shallow hydrothermal system beneath Black Diamond Pool,” the park service said. The agency noted it was not caused by volcanic activity and seismicity, ground deformation and gas and thermal emissions are still at their background levels.

The Black Diamond Pool kept its “distinct features” during the explosion, though the shape was somewhat changed, the park service said. Both the Black Diamond Pool and Black Opal Pool’s waters are murky with debris and the unstable ground is causing their edges to occasionally slide into the water, per the park service.