The Pyrenees mountain range that separates France and Spain is known for its many highly pure mountain lakes extending at the foot of imposing peaks. Lakes like Oo, Ayous, Gaube, or the lakes of Bouillouses and Bethmale only form a small part of the countless lakes of all sizes that punctuate the Pyrenean landscape. The Pyrenees National Park alone lists 169 bodies of water. Most of the mountain lakes were born after the last glaciation and the gradual retreat of the associated glaciers.