Yellowstone National Park, in all its natural beauty, is only a face mask on the underlying danger beneath. Underneath the park lies a super-volcano and boy does that puppy have some power brewing. The last time a super-volcano went off was nearly 700,000 years ago, and it happened in Yellowstone. Hopefully it doesn’t happen again anytime soon, because it would wipe out half of the country. An interesting note about super-volcanoes is that they don’t look like the traditional volcanoes we are used to seeing. Instead of being a a cone shaped mountain, they are essentially giant sunken areas of ground.