Most of western and central Austria is mountainous, and much of the flatter area to the east is hilly, but a series of passes and valleys permits travel within the country and has made Austria an important bridge between various sections of Europe. The principal topographic regions are the Alps, constituting 62.8% of Austria's land area; the Alpine and Carpathian foothills (11.3%); the Pannonian lowlands of the east (11.3%); the granite and gneiss highlands of the Bohemian Massif (10.1%); and the Vienna Basin (4.4%).
The highest point of the Austrian Alps is the Grossglockner, 3,797 m (12,457 ft). The Danube (Donau) River, fully navigable along its 350-km (217-mi) course through northeastern Austria, is the chief waterway, and several important streams—the Inn, Enns, Drava (Drau), and Mur—are tributaries to it. Included within Austria are many Alpine lakes, most of the Neusiedler See (the lowest point in Austria, 115 m/377 ft above sea level), and part of Lake Constance (Bodensee).