Add to that a whole host of seismic activity, and it becomes clear why Yellowstone is one of the most volatile places on Earth. But despite the dangers of this otherworldly landscape, it has long been a source of fascination. Home to some 500 geysers and thousands more geothermal features, it appeared as an almost hellish landscape to the white settlers who arrived there in the 19th century. Photo credit: Education Images / Universal Images Group / Getty Images