A flat itinerary starts from Grosseto and arrives in Castiglione della Pescaia, passing through what in ancient times was Lake Prile. Today, it's a vast agricultural area that was reclaimed from the marshland thanks to works begun by the Habsburg-Lorraine at the end of the 18th century and completed in the mid-20th century. The area vaunts the Diaccia Botrona Nature Reserve with Clodia Island (visitable with a small detour), the Casa Rossa Ximenes Museum, the Grand Ducal pine forest, San Felice Oasis, the Marina di Grosseto seafront and the centuries-old Castiglione della Pescaia fishing village with the striking Rocca Aragonese.
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.
Once in Castiglione della Pescaia, we recommend you visit the Casa Rossa Ximenes multimedia musem located about 2 km after the Giorgini bridge, on the embankment of the Bruna river. Back on the track (km 30.5), continue towards Grosseto on the SP 158. After 500 meters, enter the cycle path that runs along the provincial road for 7 km. At km 37, we find the Oasis of San Felice, a protected area with didactic panels on the pine forest, vegetation and animals. Here, the cycle path ends and we cross the Leopoldo canal by taking SP 158. After a few meters we take Via delle Colonie (on the right) and go towards Marina, where we advise you to leave your bike and relax on the beach. To return to Grosseto, you walk along the Marina promenade which ends at the tourist port area, and then take via Grossetana and continue towards Grosseto until you reach the crossing near the service area that brings us to the first part of the cycle path. Once we cross the SP 158 and then pass the roundabout, the wide Marina-Grosseto cycle path will take us back to the starting point in about 10 km.