Aar

The Aar (German Aare), a tributary of the High Rhine, is the longest river that both rises and ends entirely within Switzerland.

Its total length from its source to its junction with the Rhine comprises about 295 km, during which distance it descends 1,565 m, draining an area of 17,779 km2, including the whole of central Switzerland.

The Aar rises in the great Aar Glaciers of the Bernese Alps, in the canton of Bern and west of the Grimsel Pass. It runs east to the Grimsel Hospice, below the Finsteraarhorn, and then northwest through the Haslital, forming on the way the magnificent Handegg Waterfall, 46 m, past Guttannen, and piercing the limestone barrier of the Kirchet by a major canyon, before reaching Meiringen, situated on a plain.

Near the west end of Lake Thun, the river receives the waters of the Kander, which has just been joined by the Simme. On flowing out of the lake it passes through Thun, and then flows through the city of Bern, passing beneath eighteen bridges and around the steeply-flanked peninsula on which the Old City is located. The river soon changes its northwesterly flow for a due westerly direction, but after receiving the Saane or Sarine it turns north until it nears Aarberg. From the upper end of the lake the river issues through the Nidau-Büren channel and then runs east to Büren. The lake absorbs huge amounts of eroded gravel and snowmelt that the river brings from the Alps, and the former swamps have become fruitful plains: they are known as the "vegetable garden of Switzerland".

Source: en.wikipedia.org/wiki/Aar - 18.09.2011