Semsvannet

thumb|View of Semsvannet, Skaugumsåsen and Tangen Semsvannet is a lake in Asker municipality in Akershus county, southwest of Oslo, in Norway. The lake is situated close to, for the Norwegians, famous places such as the ridge Skaugumsåsen, the old cultural house Tangen and Skaugum the official residence of the heir to the throne of Norway, i.e. the crown prince or princess of Norway. The status of Semsvannet as a nature reserve was upgraded when the area was protected as a conservation area October 2, 1992. The lake and its vicinity was elected a millennium site in the year 2000.

== Numbers == Lake Semsvannet is and is situated at a height of above sea level. The greatest depth is . To the lake flows the river Gupelva. From the lake flows the river Askerelva. Regarding the inhabitants of the lake, fish, there are: Northern pike (Esox lucius), European perch (Perca fluviatilis) and Roach (Rutilus rutilus). There are also smaller populations of Brown trout (Salmo trutta), Arctic char (Salvelinus aplinus) and European whitefish (Coregonus lavaretus).