Rich with algae and greenery, a collection of dead tree trunks is known locally as the Troll Forest. A 1908 landslide jammed the Lygna River in the precipitous Norangsdal Valley near Øye, forming this pristine mountain lake, a prime spot for underwater photography. Beneath the cold, glassy waters, divers can explore remains of alpine huts with birch-bark roofs and swim under a stone bridge that was used to cross the river before it was inundated by it. (Christian Skauge)