From San Martin, and more precisely from the hamlet of Longiarù, the valley of the Rio Seres branches off, better known as the Valley of the Mills or Val di Morins in Ladin, a splendid rural area with an ancient charm. The valley is so called because of the presence along the river of numerous hydraulic machines - about 30 - once used by the inhabitants of the area for daily life and work in the fields.
Between the two villages of Miscì and Seres there is a beautiful and easy walk of about 1.5 km that takes you to 8 recently restored and fully functional water mills, equipped with sluice gates, wooden channels and crosspieces, and a water cableway. Two of these are equipped with a double wheel. Currently, only the first of the 8 mills can be visited inside.
In summer in August, the Festa dei Mulini takes place with guided tours, concerts, entertainment for children and tasting of local products.