7. Grand Prismatic Spring (USA)
This spring is the largest hot spring in the United States and the third largest in the world. It is located in Yellowstone National Park, Wyoming. It was first discovered by geologists in 1871, who gave it its name because of the coloration of the spring. The colors are those of a rainbow, which you can also get by shining white light through a prism.
Take a look at the next page for another incredible place on earth!