Near the village of Petrovo is the third in terms of water flow karst spring with water temperature around 20 ° C. It is located about 5 km from the village, in the area and “Izvora”, only 15 minutes from the hut “Izvora”. The water is clean and with excellent physical and chemical characteristics. And perhaps this is why the locals call it "Bistrets” (meaning clear).The purity of the spring is most likely due to the massive marble rocks around which it is formed. On the way to the spring, you go through a shelter with wooden benches, tables and playground. The spring itself is in a beautiful mountain setting. Every year on June 29 - St. Peter's Day, at this point, the residents of Petrovo organize their village feast.