Damtjern is a dammed lake in the forest east of Hønefoss and Steinsfjorden. The lake is very beautiful and its a nice place for swiming and fishing. (You can buy fishing card on SMS,you find instructions on the information board on the parking place). Damtjern is also a very good starting point if you want to explore Nordmarka, either by foot or with bicycle. You only pay 20 NOK for twenty-four hours of parking to the local ski club.
How to get there: from Oslo /Sandvika you follow E16 toward Hønefoss, until you get Sundvolden hotel on your right side. Take the first road to the right and follow the signs toward Åsa for ca 8,5 km then you follow the signs toward Damtjern (5 km)
Right after you drive in to the road toward Damtjern you pass a museum called kjerratmuseet, they have an exhibition of the old forest work in this parts of Nordmarka and the very special timber moving operation that took place here :) well worth visiting http://www.kjerraten.no/