Lakes that did not freeze over However, the low winter temperatures were not sufficient for Lakes Geneva, Neuenburg, Thun, Brienz, Lucerne and Walen to freeze over. There are few, if any, historical accounts of these lakes freezing over.

Lake Brienz in Switzerland rarely freezes over completely due to its immense depth and the large volume of water it holds, which retains heat more effectively than shallower bodies of water. Reaching depths of up to 260 meters, the sheer mass of water makes it difficult for temperatures to drop enough for total ice coverage. However, during exceptionally cold winters, parts of the lake—particularly the shallower sections near the shores or the inlets—can develop a layer of ice. This is quite rare, occurring only a few times in a century for the entire surface to freeze (a phenomenon known as Seegfrörni). Even in the dead of winter, the lake usually maintains its stunning, deep turquoise color, provided by the glacial particles flowing in from the Aare and Lütschine rivers. While you won't be ice skating across it, the surrounding snowy peaks of the Bernese Oberland make it a spectacular winter vista.