Most people don't know this: Yellowstone National Park is an active super volcano! And that was exactly the reason for my visit... Yellowstone sports some three hundred geysers and over ten thousand geothermal features. Yellowstone is essentially a volcanic park. Its hard to be certain which geysers are going to be active at any one time. Most eruption tables are estimates. Walking out among the various geysers in the early evening is like being on another planet! Geyser eruption