Tøyenbadet is the biggest indoor pool in Oslo with a 50m pool. For any foreigner it will be crazy…read moreexpensive: 93NOK for a single entry as an adult. The trick is to buy the card where you can either buy 6 entry at once (474NOK + 20NOK for a card to be used within one year) or charge it with money (unlimited in time) and the price will drop to 79NOK per entry. The last trick is to be a member of the gym. There are also saunas which are nice to warm up in winter.