Norwegians love being in nature and Nordmarka is the forest where Oslovians go at every opportunity. In summer, you'll meet people of all ages hiking. In winter, they can be found on cross-country skis (or pulled in pulks if they're too young to ski) along the Nordmarka tracks which stretch for miles and miles. Nothing is more Norwegian than cross-country skiing. A good starting point for hikes is Frognerseteren.