It leads us from Porrentruy southwards to the Col de Montvoie on the crest of the Jura, which separates Porrentry from the Doubs gorge at St. Ursanne. On the heights of this ridge we then ride westwards for about 15 km with alternating views of the Doubs valley on the one hand and the Ajoye on the other.
Between Roche dOr and Damvant we come across another treat that has given this tour its name. Up here, in 1886, a system of caves was discovered which was then developed for tourism. You can visit it in the company of a guide on a small, well-maintained path. Over a length of 1.5 km, stalagmites and stalactites meet each other in beauty. The highlight is the "Great Hall" with its imposing dimensions. More recently, a dinosaur park has also been attached.
This tour can be combined with the «Col de la Croix» tour, which then takes in the entire right bank of the Doubs Gorge behind St. Ursanne in a single tour.