About 20km east of Sarrebourg, the Saint-Louis-Arzviller inclined plane is one of the engineering marvels of the French canal network. Built in 1969, the water-filled caisson carries boats up and down a 44-metre slope in about four minutes, replacing the 17 locks it previously took to navigate the same ascent on the Canal de la Marne au Rhin. The mechanism is a transverse inclined plane — rare in Europe — where a tank of water containing the boat travels on rails, counterbalanced by a second tank on the other side of the slope.
Visitor boats run in the summer season, allowing you to ride the caisson. There's a viewing platform open year-round from which you can watch other vessels make the crossing. The surrounding Vosges landscape adds to the appeal.