Hats Off: Yellowstone shows off hundreds of caps blown into hot springs this year
The park draws over 4 million visitors a year, with the vast thermal pools and hot springs among the most popular attractions. But the rugged and sweeping terrain leads to consistently gusty winds, and that in turn leads to "a near-constant stream of trash and hats being blown into the delicate hydrothermal areas," the USGS said.
Yellowstone National Park
A look at the United States' first National Park: Yellowstone.
YELLOWSTONE NATIONAL PARK, Wyo. – The breathtaking beauty of Yellowstone National Park and its stunning hydrothermal features may have you exclaim: "Hold on to your hats!"
The U.S. Geological Survey asks you to take that literally.
The park draws over 4 million visitors a year, with the vast thermal pools and hot springs among the most popular attractions.
But the rugged and sweeping terrain leads to consistently gusty winds, and that in turn leads to "a near-constant stream of trash and hats being blown into the delicate hydrothermal areas," the USGS said in a social media post highlighting the work of their Yellowstone Geology Program.
Yellowstone National Park Geology Program team member Mara Reed uses a long grabber pole to remove a park map, presumably blown from a visitor's hand or pack by the wind, from a feature in Upper Mammoth Terraces. National Park Service photo by Samantha Hilburn, August 2025.
(USGS / FOX Weather)
To reach the debris, which is often literally floating in boiling water, the USGS says the team uses a collection of tools — some of which they've built themselves.
"From 2-foot to 12-foot and even 30-foot grabber poles, to fishing rods and extra-long slotted spoons, the team uses (or creates!) any device necessary to remove items safely," the USGS said. "The Geology team, who represent a range of earth science backgrounds from geophysics to volcanology to science education and more, are trained to carefully traverse Yellowstone’s dangerous yet delicate hydrothermal areas, preventing damage to fragile bacteria mats and geologic formations while also keeping themselves safe."
Just some of the hats collected by the Yellowstone National Park Geology Program from sensitive thermal areas throughout the park in 2025. National Park Service photo by Margery Price, September 3, 2025.
(Margery Price / USGS / FOX Weather)
To illustrate their work, one of the science technicians laid out the collection of over 300 hats plucked from the thermal pools just so far this year — they estimate the combined value is about $6,000.
Found your pizza…
But it's not all just hats.
"Favorite finds from the team during the summer of 2025 include a Birkenstock sandal, a pizza box with slices still inside, a fake Louis Vuitton bucket hat, a stuffed koala toy, a ball cap with the phrase 'I PEE IN THE LAKE,' and a Polaroid picture of Excelsior Geyser—which was found within Excelsior Geyser’s crater!" the USGS said.
Yellowstone National Park Geology Program volunteer Tara Cross smiles and shows off a pizza box found on Geyser Hill in Upper Geyser Basin. National Park Service photo by Margery Price, August 2025.
(Margery Price / USGS / FOX Weather)
Overall, the team estimates so far this year, they've collected over 13,000 pieces of trash while covering more than 1,300 miles of trails and boardwalks on foot and driven over 11,000 miles to reach the various thermal areas throughout the park nestled in the northwestern corner of Wyoming and southwestern Montana.
While the USGS says nearly all the litter is unintentional, some of it, such as sunflower seed shells, orange peels, and other food materials, are particularly time-consuming for the team to remove.
"Debris thrown into a hot spring can irreversibly change its behavior, resulting in lower temperature, changes to color, and altered (or halted altogether!) eruption behavior," the USGS said. "This is what caused a change in the color of Morning Glory pool, for example."
More than just trash collectors
The Yellowstone Geology Program team isn't just plucking pizza and hats from the waters, they're also perform quite a bit of science.
Yellowstone National Park Geology Program team members Samantha Hilburn (left) and Margery Price (right), both Physical Science Technicians, pose with a snow pit dug near Lewis Canyon for installation of a semi-permanent GPS site, installed in collaboration with USGS scientists. USGS photo by Dan Dzurisin, May 2025.
(USGS / FOX Weather)
"The staff use water quality instruments and a network of more than 100 temperature sensors to measure chemical composition and the eruptive activity of features across the park—information that is used by the park’s interpretive staff to help predict geyser behavior," the USGS said. "The crew also spends time installing hazard signage, remediating footprints and graffiti, supervising maintenance work in hydrothermal areas, assessing geologic damage or hazards in collaboration with law enforcement investigations, and examining scientific records and resources to answer questions from other park departments."
If you visit the park and see a team in red vests, that's likely the geology team hard at work. They are available to answer questions about their work and the science at work behind the scenes of one of America's most popular national treasures.