The Gorgo Santo is a spring that features a very rare phenomenon...
Rainwater and snow water are not retained by the Luserna Plateau due to the karst composition of the terrain; instead, it flows down the valley through tortuous underground passages. Under normal conditions, it flows from the lower Gorgo Santo cave; however, in heavy rain or snow, the cave may be unable to handle the full flow, so the water is also released from the upper Gorgo Santo cave... a sort of safety valve.
Pope Boniface IV (7th century) happened to pass through these parts during a trip and blessed the whirlpool: hence the name "santo." But there is another, more evocative and legendary, theory behind the name: it is said that here, Saint George defeated the Great Dragon that dwelt in the cave and dominated the valley!
The presence or absence of water depends on rainfall or snowfall: to find a good flow of water, you should visit on days after it has rained; otherwise, you'll visit the whirlpool in its "dry" state.