When my wife and I visited Yellowstone National Park a few years ago, we expected to see lots of geothermal activity and geisers - we were not disappointed. There are many boiling pools in the park and it is possible to get really close to them. Some have steam shooting high up into the sky. Some of them are very colorful with their rim changing from red to orange to yellow to green and blue. We had a great time exploring all the different features in the park and learning about the interesting geological structures present in it. All the wildlife around was a bonus.