In some parts of the park, geysers erupt multiple times a day while delighted tourists look on. But in others, these volatile vents lie dormant, waiting for their time to explode. And it was one such sleeping giant, known as Ear Spring, which boiled over in September 2018, sending a jet of water and debris high up into the air. Photo credit: Inger Vandyke /VW PICS / Universal Images Group / Getty Images