The first time I saw Mammoth Springs in Yellowstone I was blown away. There is an eeriness to it- almost like it's from another world. Combine that with signs telling you to stay back (unstable grounds atop acid are not made for walking on) and you can't help but be intrigued. What's more is that when the sun hits it just right, the whole place seems to glow from within and glistens like it's been dusted by gold and silver. It's absolutely breath taking.