Three mountain ranges form the south eastern border of the Department of Tarn. The pasture land of the Lacaune Mountains has streams and rivers for fishermen and canoeists. Ancient Sidobre in the heart of the Haut-Langedoc Regional Nature Park - the largest granite plateau in Europe - is best explored on foot or by mountain bike. Here huge strangely-shaped rocks with names like 'The Three Cheeses' carved by wind and weather lurk amongst the woods and deep river valleys. Some peaks in The 'Montagne Noire' can rise to 3500ft.