Largest hydrothermal explosion crater

Hydrothermal explosions are caused when underground water is subjected to very high temperatures and pressures by interactions with molten rock. When this superheated water reaches close to the surface of the Earth, the resulting drop in pressure can cause an explosive expansion of the water into steam. The Mary Bay explosion crater complex in Yellowstone National Park, Wyoming, USA, measures 2,000 x 1,000 m (6,336 x 3,168 ft) and was formed around 14,000 years ago by a series of hydrothermal explosions.