After Missoula, we made our way to Yellowstone. The first stop was Mammoth Hot Springs. We stayed in the old hotel there in the park, saw some elk, learned a little bit about the thermal features of Yellowstone. The biggest hit was something called the Boiling River. It is a place where a pretty sizable hot spring flows into a river. With the river water being very cold and the hot spring being very hot, you can sit where they merge and find exactly the right temperature that you desire. It is a hot tub without the chlorine. If you ever make it to Yellowstone, find this. It was the highlight of the day.