The park service warned visitors to stay away from the hot pool after a human foot was found there.
One of the deepest hot springs in the park was where the partial foot was found.
Law enforcement officers at the park are investigating.
Evidence from the investigation suggests that an incident may have taken place on the morning of July 31, 2022.
The park thinks there was no foul play.
Accidents are not uncommon in the thermal pools of the national park.
A young man fell into a hot spring after slipping off a boardwalk.
Two people had to be treated after being scalded by water.
The park service advised visitors to stay on boardwalks and trails in thermal areas and to exercise extreme caution around thermal features.
There is hot water just below the surface of the ground.
Last year, more than five million people visited the park, which is spread across Wyoming, Idaho, and Montana.
Half of the world's active geysers, including Old Faithful, are located there.
Agence France- Presse.