If you are looking for a really steep walk, probably the best view over Ringerike and Steinsfjorden and a special nature experience then Mørkonga is the place to visit. :) Mørkonga is a crack in the mountain wall where you can climb inside the mountain to the topp. Mørkonga by it self is about 300 meters long and the path leading up to Mørkonga is ca 2 km , Mørkonga is easy climbing and no climbing experience is needed, but if you don't like steep walking this is not for you.
After you reach the top you can walk ca 2 km to Skardertjernet and go back down from the mountain that way(less steep), the path to Skardtjernet is blue-marked by DNT but the path back down to the parking place is not, so you can easily miss it. But if you know about it it is easy to find. After walking for about 2 km the path changes form and locks more like a «wagen road» and you see Skardtjernet to your left, and right is back to the parkingplace :) if you keep on following the blue-marked path past Skardertjernet you will get to Retthella and Kleivstua. You can also take a little longer walk to Gyrihagen witch is a very nice viewpoint. On the way to Gyrihaugen you also pass migartjern which is a great place for a swim.
How to get there: from Sandvika/oslo you drive E 16 toward Vik and Hønefoss until you get sundvolden hotel on your right side take the first to the right after the hotel and follow the road with steinsfjorden on your left for 6 km. Right after you pass the second «ferist» (cow and sheep barriers laid down in the road) you get a small parking place on your left side and the blue marked path start from there