From Piantravigne, take the road that was taken on the outward journey until you reach Borro della Fornace once again and continue along the path.
The itinerary partially leaves the countryside and gets closer to the wood as it approaches the source from which the route's name is taken: the Sorgente dell'Acqua Zolfina is a natural spring of sulphurous water, recognizable even from a distance due to its scent of sulphur.
After passing the source, you dip into the wood for a small stretch, leaving behind the view of the Balze and instead greeting the Mediterranean scrub. The forest ends when you approach the Sette Ponti provincial road, which is the last stretch of the itinerary and leads to Castelfranco di Sopra and the starting point.
For more information on the characteristics of the route, visit: caivaldarnosupreste.it