Bus de la Spia
A water siphon fed by hereto unexplored galleries is one of the most striking phenomena in the Bus de la Spia
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The Bus de la Spia has been renowned since the Middle Ages and is one of the most popular destinations in the area amongst hikers, both because of the ease with which it can be reached (just a few minutes away from Sporminore) as well as because of the beauty of the lakes in its upper gallery and the striking phenomena that take place at the back of the cave, caused by the lake's movements. One of these is the large water siphon which closes off the gallery 300 m from its mouth. A one-of-a-kind phenomenon in Italy, it comes to life at fairly regular intervals during the day - once every 6-7 hours - and can be admired throughout the year. Slowly, as the water level starts to rise, deep rhythmic echoes begin to sound as air bubbles are expelled from its depths. The water takes approximately 45 minutes to climb up 10 m along the gallery, before slowly subsiding and triggering another extraordinary concert of sounds.
The siphon is fed by galleries which remain hereto unexplored, in spite of several attempts made by expert cave divers.