Name for the three water bodies located in the northern Alpine foreland: Obersee, Untersee and Seerhein. These are two different but spatially close lakes, which are connected by the section of the Rhine known as the Seerhein. Both lakes have a bank length of 273 km, of which 173 are in Germany, 28 in Austria and 72 in Switzerland. Together they cover 536 km², which stretch between Bregenz (Vorarlberg, Austria) and Stein am Rhein (Schaffhausen, Switzerland). Both lakes are crossed by the Rhine; the main tributary of the Upper Lake is the Alpenrhein, the outlet of the Upper Lake is the Seerhein - which in turn is the main tributary of the Lower Lake - and the outlet of the Lower Lake is the Hochrhein.
The climate is characterised by mild temperatures with moderate courses due to the balancing effect of the large body of water. Viticulture is practised around the lake. The most common grape varieties are Spätburgunder, Müller-Thurgau and Weißburgunder. The vineyards belong to different growing areas; however, the similarities within the region are greater than those with the base areas, some of which are far away. In Germany these are the area of Lake Constance in the Baden growing region, and the areas of Württembergischer Bodensee and Bayerischer Bodensee in the Württemberg growing region. These are the highest situated vineyards in Germany between 400 and 560 meters above sea level. In Switzerland these are Rheintal in the canton of St. Gallen and Untersee in the canton of Thurgau. In Austria these are some farms in Vorarlberg (mountainous region of Austria).