The Trenta Valley was once home to three gods, Triglav, Jalovec and Mangart. They were good and often helped the locals.
One day, an evil giant called Vodobruhec came to the valley. Water gushed out of his mouth and many villages were flooded. The locals complained to the god Jalovec, but he could not tame him. He called the other two to help. The three of them managed to catch the Vodobruhec, tie him up, imprison him in a cave and open his mouth so that he could irrigate the valley.
Water still gushes out of the cave in the form of the source of the Soča River. When the giant has served his time, the Soča will dry up.