The colors in Yellowstone are pretty amazing. The clear blue pools with swaths of orange around them make for great pictures. I arrived at this particular pool pretty late in the day, so the lighting was pretty flat. This did serve to illuminate the colors well. To get this shot I crouched down low on the boardwalk so the stripes of orange would create a lot of depth in the image. I decided to darken the image by .33 ev so the skies would be better exposed than what the camera originally metered for.
A big tip for shooting in Yellowstone: get up early. Everyday we would get up before sunrise and there was very little traffic. As it gets later in the day there are crowds of people everywhere.