Lac de Longemer (Longemer's Lake) is surrounded by mountains and forests. Its waters are supplied by the Vologne, which has its source not far from there, at the foot of the Hohneck. Oblong in shape, the lake's name means Long Sea. It is also called the mirror with a thousand reflections because of its morning brightness. In winter, light mists cover it. At the edge of the lake, the Saint-Florent chapel is a former 15th-century hermitage, considered the first dwelling in the area. The Lac de Longemer is one of the largest in the Vosges mountains and is classified as a protected natural site.