Oslo is surrounded by wooden hills, a sacred place for us locals which we use for exercise, relaxing and just to escape. And the best of all is that parts of this area, Marka, is just a short subway or bike ride away.
In winter the main activity in this area is cross-country skiing but it is still possible to go walking close to Sognsvann. One of my favourites is to head up to Vettakollen. The signposted trail starts by Sognsvann lake (take the the subway to Sognsvann and take the path to the left just by the shop by the lake and then left again) and it’s about 4km to the top, which opens up to one of the best views of Oslo. To the west you see the skijump arena at Holmenkollen, looking down from above!
For the complete Norwegian experience, pack a little picnic with some oranges, a thermos with hot coffee and the Kvikk Lunsj chocolate bar to eat at the top!
From the top there are a few options back down, I tend to tend back to Sognsvann but you can also go to Vettakollen subway station or continue over to Holmenkollen (all signposted).
The trail is a mix of gravel path and more rough paths and will be snowy so wear good solid boots and wrap up well. Also, avoid walking directly in ski tracks if possible, these are very much sacred to the locals!