Yellowstone National Park is a truly amazing place. If you've never been there, put it on your bucket list. It's huge, too much to see in a day, so we took 2 days.
On the first day, we started at Old Faithful and walked a lot around the thermal features near there. There are lots of pools of colored water, and the colors are due to the different creatures living in it, at different temperatures. Several of the pools are geysers, and erupt occasionally, some regularly and some very rarely.
We also went to Mammoth Hot Springs. As we were driving in, we got caught in a traffic jam due to a tourist who approached a bison for a picture. He was gored, thrown into the air, and then trampled. He was on the ground being tended to by EMTs when we arrived, and the bison was grazing nearby. Then the rangers arrived and used two jeeps to drive the bison away. They lose one or two tourists that way every year, and they are very serious about not getting close to the animals, or feeding them. When I was a lad, we went to Yellowstone and the bears would surround the cars and beg for food. No more, they are wild again and don't bother the cars. We didn't even see any bears, but we did see a family of elk crossing the street and settling down in the shade.
Mammoth Hot Springs is big mounds and terraces built up by deposits of minerals from the springs. They make some colorful and interesting shapes.
They've posted signs around some areas of the park that had been burned in the big fire in 1988.
As if the need for reseeding had not been caused by the fire itself !! Reminds me of the BP commercials telling all the wonderful things they've done for the Gulf Coast.
On the way back, we saw a big bull elk next to the road.
More pictures here.