Fiskumvannet is a 2.5 km long, shallow and nutrient-rich lake, surrounded by woods and farmland. It is among the best and most popular birding lakes in southeastern Norway. The northern and western shores are marshy and partly flooded at times, overgrown with reeds and other kinds of lush water vegetation. Fiskumvannet is connected with the much larger and deeper Eikeren lake through a narrow strait. This is one of the best birding sites in Buskerud county. It is equipped with a tower hide, reached along a (often very wet) footpath.