The Most Common Trash Removed From Yellowstone Thermal Areas Might Surprise You
Humans unfortunately tend to litter, even in beautiful and historic places like Yellowstone National Park. While you may suspect plastic water bottles or cigarette butts to be the main offender, it's actually a peculiar clothing item that gets left behind the most.
In the most recent edition of the Yellowstone Caldera Chronicle, a weekly column written by geologists and scientists from the Yellowstone Volcano Observatory, Margery Price details how Yellowstone's Geology Program takes care of the park and cleans up after the four million tourists who visit each year.
Hat Pollution Is a Big Problem
"This immense amount of visitor traffic combines with the area’s intense winds to create a near-constant stream of trash and hats that blow into delicate hydrothermal areas," Price wrote. The Physical Science Technician shares that in 2025 alone, 13,000 pieces of trash were collected throughout the park -- including 300 hats.
The hydrothermal ponds that fill Yellowstone park are incredibly dangerous to touch. One 17-year-old visitor fell into a geyser in June and was sent to the hospital with significant burns to his foot and ankle. The extremely hot temperatures of the thermal pools makes retrieving a lost hat pretty much impossible without the right equipment.
"To reach this debris, which is often literally floating in boiling water, the Geology team uses a collection of tools," Price details, "30-foot grabber poles, to fishing rods and extra-long slotted spoons, the team uses (or creates!) any device necessary to remove items safely."
Park rangers estimate that around $6,000 worth of hats were lost or left behind in Yellowstone in 2025 alone, including a fake Louis Vuitton bucket hat and a ball cap that reads "I pee in the lake."
Other Litter Is Even More Time-Consuming to Clean Up
While hats are a fun surprise for the cleanup crew, they're not the worst of the issue when it comes to manmade pollution in the park. "Nearly all of this litter is unintentional," says Price, "although sunflower seed shells, orange peels, and other food materials discarded by the occasional visitor accumulate as well and are particularly time-consuming for the team to remove."
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