With a surface area of 54ha and a depth of up to 48m, Lake Allos is the largest natural lake in Europe at this altitude (2 228m). You can walk around it in 1hr (allow a further 45min to get to the lake and back). Famous for its azure colour, the water held by a glacial rock bar comes from melting snow and several springs. Below, at the Laus Plateau, another glacial lake has given way to a peat bog.