Lower Lake Constance

The Untersee (German for Lower Lake), also known as Lower Lake Constance, is the smaller of the two lakes that together form Lake Constance and forms part of the boundary between Switzerland and Germany.

Lake Untersee measures 63 km² and is situated about 30 cm lower than the Obersee. The Romans called it Lacus Acronius. In the Middle Ages, the Upper Lake was called Bodamicus Lacus, or Bodensee in German. At some point in time, this term began to include the Lower Lake, and a new term "Upper Lake" (in German: Obersee), was introduced for the larger lake.

The main tributaries are the Seerhein and Radolfzeller Aach. The landscape surrounding the Untersee is very diverse. The Untersee contains two islands: Reichenau and Werd (near the transition to the High Rhine). In the northeast is found the Bodanrück peninsula; in the northwest, the Hegau lowlands with the Mettnau peninsula; in the west, the Höri peninsula, with Mount Schiener Berg, and in the south, the Seerücken, which reaches more than 300 feet above the Untersee near Berlingen.

Bordering Lake Untersee are the Swiss cantons of Thurgau and Schaffhausen and the German state of Baden-Württemberg. In contrast to the Obersee, the border between Germany and Switzerland across Lake Untersee is well defined. Municipalities on the Swiss side are Gottlieben, Ermatingen, Salenstein, Berlingen, Steckborn, Mammern, Eschenz and Stein am Rhein. Municipalities on the German side are Öhningen, Gaienhofen, Moos am Bodensee, Radolfzell, Reichenau, Allensbach and Constance.

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