Yellowstone National Park contains one-third of the world’s geysers and one-half of the world’s thermal springs.
The park makes great effort to enable you to walk up to them as close as is sensible, and in most cases that means you can feel the steam and hear the bubbling.
I’ve gathered just a few of the more interesting pools that we’ve passed.
I’ve already shown you a ground-level picture of Grand Prismatic Spring, at 370 feet diameter and 121 feet deep, the largest thermal spring in the US, and third-largest in the world. Its colors match the rainbow dispersion of white light by an optical prism: red, orange, yellow, green, and blue.