The itinerary starts from via della Repubblica in Grosseto and continues towards the Grosseto-Marina cycle path, bringing us to the center of the area that was formerly soaked by Lake Prile, which became marshland over the years. The reclamation works were begun by the Grand Duke of Tuscany Pietro Leopoldo di Lorena, who entrusted the work to the Jesuit astronomer and engineer, Leonardo Ximenes (1716-86). The works continued in the nineteenth century under the engineers Vittorio Fossombroni and Alessandro Manetti, who added the bridging system to the sluice system that was already in use. The new method involved the using the muddy waters of the Ombrone and Bruna rivers, which were made to flow into defined marshy areas and left to stagnate in order to deposit the mud. Once you enter the cycle path, pedal the first 6.5 km, then the track bends to the right and crosses the Strillaie municipal road. Proceed on the Strada delle Strillaie for 2.5 km, and then take the Strada Comunale di San Vincenzo to Elba which at km 11 leads to the SP 80 del Pollino. Continue towards Grosseto for 500 meters, and then cross the provincial road in Casotto dei Pescatori (refreshment point) to enter the vast agricultural area of Squadre Basse. The GPS track bends to the left at km 12.300, and then continues on the Strada Vicinale Squadre. At km 15,300 the ground changes and goes from asphalt to a dirt track and the name of the street becomes via del Padule Aperto. Between km 18 and 19, you arrive at the hill that in ancient times was Clodia Island. Here, we can admire the ruins of the Benedictine Abbey of San Pancrazio al Fango, built in the early Middle Ages on the ruins of a Roman villa that was built by Clodio in the mid 1st century BC, hence the name of the ancient island of Lake Prile on which it stood. We are now in the protected area of the Diaccia Botrona Nature Reserve, a naturalistic oasis that's noted in Europe. We continue the route by following the track. At km 20, we cross the Bruna river in Ponte di Badia. We take the SP 3 del Padule for just a few meters before heading inland and turning onto the SP 23 delle Strette. We then return to municipal roads (km 22) that will lead us to the center of Castiglione della Pescaia.