Access to West Thumb Geyser Basin was closed to the public on Wednesday after a Yellowstone National Park employee reportedly found human remains floating in one of the areas thermal features.
Park officials said an investigation is underway into the incidents.
The park employee apparently spotted a shoe floating in Abyss Pool in the geyser basin where water temperatures can reach over 170 degrees. The shoe was reported to still contain the partial remains of a foot.
Abyss Pool is the deepest hot pool in Yellowstone at 53 feet.
Thermal features in Yellowstone contain high levels of corrosive acid that has been known to dissolve the bodies of people who perish in them.
In 2016, a 23-year-old Oregon man slipped into a hot pool in the Norris Geyser Basin and succumbed. Attempts to retrieve his body immediately were unsuccessful and by the next morning his remains had dissolved.