The waters of the Flumen torrent have hewn out gorges, creating a series of waterfalls. The most stunning of these can be seen from the road, between the tunnel and the Chapeau de Gendarme rock formation. The D 436 skirts these famous gorges from Saint-Claude to Septmoncel, commanding impressive vistas of them along the way. The road passes through a rocky spur via a tunnel, before presenting you with a view, in front of you, of the main Cascade du Flumen.