Intermittent Spring, also known as Periodic Spring, is a rhythmic spring in Swift Creek Canyon in Star Valley near Afton, Wyoming, and is regarded as the largest rhythmic spring in the world. Its flow starts and stops in a repeating cycle, making it a rare natural phenomenon and one of the area’s best-known attractions. Local tradition says it was discovered by the great-great-grandfather of wrestler Rulon Gardner while logging and searching for fresh water. The leading explanation for its pulsing flow is siphon theory, supported by University of Utah studies that hydrologist Kip Solomon said strongly backed the idea.