Lake Geneva is divided into three parts because of its different forms of formation (sedimentation, tectonic folding, glacial erosion): According to the Swiss Federal Office of Topography, swisstopo, "Lac de Genève" designates that part of the "Petit Lac", which lies within the cantonal borders of Geneva (excluding the cantonal exclave Céligny), so about from Versoix–Hermance to the Rhône outflow in Geneva. The Chablais Alps border is its southern shore, the western Bernese Alps lie over its eastern side. The high summits of Grand Combin and Mont Blanc are visible from some places. Compagnie Générale de Navigation sur le lac Léman (CGN) operates
Swiss Alps on the shores of Lake Geneva to Rorschach on the shores of Lake Constance, passing close to the cities of Thun and Lucerne. The not well defined regions in Switzerland that lie on the margin of the Alps, especially those on the north side, are called the "Swiss Prealps" ("Préalpes" in French, "Voralpen" in German, "Prealpi" in Italian). The Swiss Prealps are mainly made of limestone and they generally do not exceed . The Alpine cantons (from highest to lowest) are Valais, Bern, Graubünden, Uri, Glarus, Ticino, St. Gallen, Vaud, Obwalden, Nidwalden, Schwyz, Appenzell Innerrhoden, Appenzell Ausserrhoden, Fribourg, Lucerne and