The Haldanen (Q. "Hidden Stream") was one of the streams that fed the upper course of the Lefnui in Anfalas, The stream defined the southern boundary of the Nan-i-Feryth and had its source in both the Pinnath Gelin and the great arm of the White Mountains that guided the upper Lefnui southwards. For the greater part of its course, the Haldanen was shielded from view on either side by wooded hills, unlike the other tributaries of the upper Lefnui, which flowed through open country; hence its name.The Haldanen possessed no fords, but was shallow enough to cross at several places.