You can reach Sussia starting from Vetta by following the forestry road or alternatively by a well-marked path which starts a little lower, at Frasnito. From the church of San Michele in Sussia, either take the path to the left or climb to the right until you reach the birthplace of the guide Antonio Baroni before again taking a left, then follow the path directly to Mount Zucco all the way to the Chapel of the Grosnello where the road from Catremerio (988 m) ends. From here, next to the shrine take the path which is fairly easy except for the last steep section up to the peak of Cerro (m 1285). To note are the splendid circle of trees used in bird hunting (Spadi) which the path passes and the "Laca the Roculì" (deep cave about 300 m).
Alternatively, you can also climb to Cerro directly from Sussia: take the path which goes towards Foldone and then leave almost immediately for the trail which climbs steeply to the left and is connected to a path which ascends from Grosnello.