The Arzino stream is one of the last Alpine watercourses to retain a high degree of naturalness. Its 28 km are almost entirely included in the municipality of Vito d’Asio. It rises at the foot of Mount Teglara, in the locality of Fontanon, and crosses the Val di Preone with a series of spectacular waterfalls, flanked by a path that is easy to follow on foot (just be careful not to slip – sentiero delle cascate).
The stream, which is still wedged in the valley, flows past the village of Pozzis and opens out at San Francesco. It collects a number of lateral tributaries and widens out into the splendid Curnila pools, which have now become a popular bathing spot (they were also mentioned by the Financial Times as one of the best places for wild swimming). The Arzino picks up speed with the gradient, slowing down at Casiacco, before flowing into the Tagliamento at the Stretta di Pinzano.