The Regional Natural Park includes a protected area following the Sile river, the longest European river originating from natural springs, which crosses the Veneto plain along some towns of the provinces of Treviso, Padova and Venice. It is a course many kilometers long, commencing before Treviso, in the Casacorba locality. Here the water spontaneously sprouts from the ground, creating the so called "Fontanassi", the word in Treviso dialect used for the springs. Small lakes and marshy areas, peat bogs and waterways criss-cross in a thick network, distinguishing a natural environment of extreme interest and charm.
Just before Treviso, in Santa Cristina di Quinto, the courses of the Sile and the Piovega brook surround a marshy island of extreme beauty, protected with the creation of the Natural Oasis of the Cervara Mill. This small natural reserve is a biotope of great natural value, classified as a Site of European Significance (S.I.C.) since wild fauna finds refuge here and the spontaneous flora of the Sile can be protected.
After passing the town of Treviso the landscape begins to evolve, and the traces of a thousand-year old history and of human settlements become evident. Here we find the old mills which supplied Treviso and Venice with flour and were used for the paper mills and the workshops of the area, while the splendid villas built by the Venetian noblemen between 1400 and 1700 continue to be mirrored in the water of the river.