From the parish church of San Martino in Fondo, walk down to the stream near an old mill. From here, take the valley that has been carved into the rock by the Rio Sass river, whose unwavering flow will accompany you throughout the duration of the hike in the ravine. Walk alongside the water course on a convenient beaten track where from time to time you will come across marks left by man, such as an old mill with its large wheel that is still working to this day, and the wonders of nature. The trail then becomes narrower and ends with a short walkway and a few metal steps to reach the level of Lake Smeraldo. Once here, we suggest you walk all the way around the small yet fascinating basin and then walk back the way you came. On your way back, you can come out in the centre of Fondo, walking through the beautiful square that houses a large and precious water clock, and then make your way back to the church.