St. Ursanne is a small medieval town and the third historic town in the canton of Jura after Delémont and Porrentruy. Town gates and town houses dating from the 14th to 16th centuries characterise the townscape. You leave St. Ursanne via the Doubs and the stone bridge built in 1728. A short time later, the river makes an abrupt change of direction. This may also be the reason why the Romans once called the meandering river the Doubs. The word comes from the Latin "dubitus" - the hesitant, the doubtful.

Further along the paved road, take a look back at the 44-metre-high railway viaduct with its 12 vaulted arches and a length of 237 metres. After La Lomène, the paved road turns into a gravel road. This section of the Doubs on Swiss territory is home to Switzerland's rarest fish: the apron, also known as the King of the Doubs. The population of this strictly protected species, which is only found in the catchment area of the Rhone, was estimated at 50 to 150 adult specimens in 2012. At the next loop, you change to a small path. After about one and a half hours, the campsite with its restaurant by the name of Tariche is located on the other side of the river. Here, you can cross the Doubs under your own steam by means of a winch and a skiff.

Secluded spots, lush meadows, trees entwined with ivy and moss invite you to linger along the route at Sous les Roches. You cross the bridge to change sides of the river again. A little later, the scenic path turns into a paved road. Passing "Bief du Moulin", the three mills, of which only one remains, you reach the village of Soubey a little later after just under four hours hiking time. The village centre is characterised by old houses dating from the 17th to 19th centuries. The Saint-Valbert parish church, built in 1632, is the only Swiss church north of the alps with a roof made of limestone slabs.