Lake Constance (Bodensee) is a large body of water located in the Lake Constance Basin within the Alpine Foreland. It consists of three distinct bodies of water: Upper Lake Constance (Obersee), Lower Lake Constance (Untersee), and a connecting stretch of the Rhine known as the Seerhein. The lake is situated at the northern foot of the Alps where the Rhine River flows.
The lake serves as a geographical meeting point for Germany, Switzerland, and Austria. Its shorelines are shared by the German states of Baden-Württemberg and Bavaria; the Swiss cantons of St. Gallen, Thurgau, and Schaffhausen; and the Austrian state of Vorarlberg. While these countries share the shoreline, the exact locations of the international borders within the lake remain a subject of dispute among Austria, Germany, and Switzerland.