The Grand Canyon of the Yellowstone River expresses the park's complex geologic history in dramatic colors and shapes. Puffs of steam mark hydrothermal features in the canyon's walls. The Upper and Lower Falls of the Yellowstone River add to the grandeur of the unique natural treasure. Experience the canyon from a variety of overlooks, at different times of day, and at different seasons. A number of trails and walkways wind along the rims and down partway into the canyon.