Workers at the park discovered a shoe containing a piece of a foot on Tuesday in a hot spring in Yellowstone.
The West Thumb Geyser Basin region, which includes the Abyss Pool where the shoe was found,
was shut down after the discovery but has since been reopened, according to the Associated Press.
The Guardian reports that Morgan Warthin, a park spokesperson, said on Thursday that the investigation into the incident is ongoing but withheld any further details.
Officials of Yellowstone National Park did not immediately respond to an insider's request for comment.
According to the resort's website, the Abyss Pool, which has a depth of 53 feet, is one of the deepest pools in the park.
Visitors are advised to stick to boardwalks and authorised trails since hydrothermal water can inflict serious burns, according to a sign on the park's website.
"You are responsible for your safety," the website adds. "Think about safety before you act. Region around Yellowstone is dangerous."
In Yellowstone, geysers and hot springs are common sights.
More than 20 people have reportedly died in Yellowstone from severe burns after falling into hot springs, according to the National Park Service.
On TikTok in 2021, a doctor offered an explanation for the puzzling presence of human feet on beaches in the Pacific Northwest.
According to Dr. Karan Raj, animals that hunt in watery environments like oceans tend to prey on weaker body parts like ankle ligaments.
Due to the buoyancy of modern sneakers, this particular body part can float and wash up on the coast.