If you like ice skating, visit the skating rink "Spikersuppa" in the city centre, close to the National theatre. The rink has music, and offers skate rental. There is also a larger skating rink with music and skate rental at Frogner Stadium, right next to Vigeland Park. Both rinks are open in the evening.
If the waters and lakes freeze over, it is also possible to go skating in the Oslo forests. Make sure the ice is safe: It should be at least 10 cm (4 inches) thick. Popular waters for skating are Sognsvann, Bogstadvannet, Nøklevann, Østensjøvannet and Maridalsvannet.