The breathtaking beauty of Yellowstone National Park and its stunning hydrothermal features may have you exclaim: "Hold on to your hats!" 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. Just some of the hats collected by the Yellowstone National Park Geology Program from sensitive thermal areas throughout the park in 2025. Yellowstone National Park Geology Program volunteer Tara Cross smiles and shows off a pizza box found on Geyser Hill in Upper Geyser Basin. More than just trash collectorsThe Yellowstone Geology Program team isn't just plucking pizza and hats from the waters, they're also perform quite a bit of science.