Featuring all the colors of one of those giant jawbreakers you ate as a kid, Yellowstone is home to two-thirds of the world's 900 geysers and is totally going to blow someday. Steam rises from the ground. Groundwater shoots hundreds of feet into the air. Mud puddles boil.
And of course, there are geysers galore:
near the Fountain Paintpot en route to Old Faithful
Old Faithful, pre-eruption
Old Faithful, mid-eruption
And finally the two geysers that appear to have been named specifically for my brother:
Also, if you step on a geyser, you are so fucked: