A partial human foot still in its shoe, found floating in a Yellowstone National Park hot spring this week, likely belong to an individual who fell into Abyss Pool on the morning of July 31.

The park said in a Facebook post that it is still investigating the death but doesn’t believe foul play was involved.

The park cautioned visitors to “always stay on boardwalks and trails in thermal areas.”

Abyss Pool is one of several hot springs in the West Thumb Geyser Basin, just off the West Thumb of Yellowstone Lake, as CrimeOnline previously reported. The pool is 53 feet deep — one of the deepest in the park — and its temperature is usually around 140 degrees, park officials say.

The park’s website explains that in hot springs like Abyss, scalding hot water from below the surface is constantly rising to replace cooler water at the surface, then cooling and sinking — a circulation that helps prevent the kind of eruptions like those seen at the park’s many geysers.

Abyss, however, erupted for the first time in its recorded history in August 1987, then several more times between September 1991 and June 1992, with one of those eruptions reached 100 feet high. The spring has not erupted again since 1992.

The floating foot was found by an employee on Tuesday, the park said, prompting the temporary closure of the West Thumb Geyser Basin and its parking lot.

The park notes that visitors should stay on boardwalks and trails, especially near any of the hot springs and geysers. The ground in those areas is fragile and thin, the park says, and a slip can send a visitor into the scalding water just below the surface.

[Featured image: Abyss Pool. (Diane Renkin/National Park Service via AP)]