Soda Springs, Idaho

Soda Springs has the only captive geyser in the world. It was discovered in an attempt to find a hot water source for a swimming pool. In 1937, the drill broke through and unleashed the geyser.
Unlike Old Faithful or many other geysers, this geyser is a cold water geyser. Its power comes from carbon dioxide gas mixing with water in an underground chamber. The geyser is capped and controlled by a timer. It erupts every hour on the hour.