The biodiversity of Switzerland’s rivers and waterways is under serious threat. However, some incredible species live under the water. The EUROPA stamps plunge us into the depths of Switzerland’s rivers and waterways. The first stamp features a whitefish species, the Balchen, a freshwater fish found only in Lakes Thun and Brienz. The second stamp shows two endangered species living in the waters of the River Doubs: the white-clawed crayfish and the Zingel asper, Switzerland’s rarest fish. Two experts from the Eawag water research institute provided scientific support for the development of the stamps. According to the Federal Office for the Environment, underwater fauna and flora are under threat: one in five species is facing extinction or has already disappeared.