One warm summer weekend we (Arild and me)  paddled the waterway through "Nordmarka", the backcountry next to Oslo. The route we chose is a classic paddling route in this area ("Mylla" to "Skar"). This does not mean it is a busy route: We met one other canoe going our way. I strongly recommend the trip, however it might be a good idea to use a lightweight canoe. Some of the land-crossings were tough with a heavy canoe. A detailed drawing of the route can be found here.