The Yellowstone River at this point is only about 15 miles from its origin in Yellowstone Lake. Here it drops 308 feet, at the upper end of the scenic wonder known as the Grand Canyon of the Yellowstone. This drop is nearly twice that of Niagra Falls. The yellow walls of this canyon gave the river, and ultimately the National Park their names.
In terms of scenic grandeur it is far and away the best thing in Yellowstone National Park. However, most park visitors never see it, preferring the thermal features around Old Faithful. If you go to the park, don't feed the bears, and don't miss the Grand Canyon of the Yellowstone.