Fountain Paint Pot & Jet Geyser were actually the first places I visited the night I got to town, and it’s the first area you’ll hit if you head east at the first turn inside Yellowstone (entering from the west). I didn’t want to head too deep into the park since I’d been on the road all day, but this place was amazing to see during sunset. Since up until that point I’d never seen geothermal activity in person, the entire area looked like a warzone with all of the steam rising into the air, and the earth boiling.
Mammoth Hot Springs is the largest known carbonate-depositing spring in the world, and gets its water from Norris Geyser Basin. It took me a little over an hour to adventure around all of the boardwalks and see everything. Overall the area is pretty impressive, but there isn’t a whole lot of diversity in what you’re going to see here. It’s at the very end of the park, depending on where you start. I don’t feel like I would have missed much if I didn’t check it out, but since I was in the area I felt it was worth a drop in at least.