Mud pots form over fumaroles whose acid gases decompose rocks into mud and clay. Lower Falls entering the Grand Canyon of the Yellowstone River. Since the late 1800's Yellowstone has been a mecca for travelers. The world's first national park was soon a popular success. These folks hiked into the Grand Canyon of the Yellowstone, where Uncle Tom Richardson served their picnic.
Mountain whitefish are also park natives.
Scenic boardwalks allow visitors to come within a few feet of active geysers.