The Alps are divided by rivers and other topographic features into more than 40 subunits for which local names are commonly used. Well-known groups in the W Alps (from the Riviera to the Great St. Bernard Pass) include the Maritime, Ligurian, Cottian, and Graian alps, the Mont Blanc group, and Valle d'Aosta. The highest western peaks are Mont Blanc, Mont Pelvoux, Monte Viso, and the Gran Paradiso; the chief routes across this section are via the Mont Cénis Tunnel and the Great and Little St. Bernard passes. The Central Alps (between the Great St. Bernard and Brenner passes) include, in the south, the Pennine, Lepontine, Phaetian, and Ötztal alps; and, in the north, the Bernina, Glarus, Allgäu, and Bavarian alps. The principal peaks of the Central Alps are Monte Rosa, the Matterhorn, the Finsteraarhorn, the Jungfrau, and the Wildspitze; the chief routes are the Simplon Tunnel and the St. Gotthard, Grimsel, Furka, Splügen, Bernina, and Brenner passes. The E Alps comprise, in the south, the Dolomites, the Carnic Alps, and the Julian Alps; and, in the north, the Hohe Tauern and Niedere Tauern; the principal eastern peak is Grossglockner. Most major routes across the E Alps follow the Brenner and Semmering passes.