Midway Geyser Basin featuring the 370-foot-wide and 121-foot-deep Grand Prismatic Spring, which is the largest hot spring in Yellowstone (Temperature 142-160°F). The Yellowstone National Park is one of my favorite protected parks in the world with walkways established for public safety and to protect fragile formations that have formed over thousands of years. This unmissable wonder of the world centers a white bottom and gem-like, blue colored pool. Minerals flow wild and bright.