The valley of the Ardèche is very scenic, in particular a 30km section known as the Ardèche Gorges. The walls of the river here are limestonecliffs up to 300m high. A kayak and camping trip down the gorge is not technically difficult and hugely popular in the summer, so much so that control of numbers is becoming a headache for park authorities.citation needed The most famous feature is a natural 60m stone arch spanning the river simply known as Pont d'Arc (arch bridge).