Yellowstone Caldera, United States of America
The Yellowstone Caldera features the popular geysers and sulphur hot springs of the famed National Park. Unfortunately, a huge danger lies beneath – one that is hard to imagine. This is where the actual volcano stands. It is one huge bomb that if and when it erupts, it is said to wipe off the whole western side of America from the map. This is how powerful this super-volcano can be. Unlike the traditional one, this kind does not have a vent on the surface.