A wonderful nature experience the Oslo Fjord with guide! båtOpplevelse AS (boatAdventure AS) sightseeing boats have daily departures from Oslo all year round, Rådhusbrygge 2, the pier just below Oslo City Hall. I recommend the 3 hours boattrip to see the grand historic Oscarsborg Fortress and alle the other beautiful islands of the Oslo Fjord. On the sightseeing boat you can taste or buy "food-souvenirs" as whale, dried Stockfish, etc ...and the have delicious fish burgers!! The sightseeing boat also stops at the museums of Bygdøy. (example: Kon-Tiki, The polar ship museum Fram and The Norwegian Museum of Cultural History) ...Nice trip! Not so expensive, and a friendly crew and a funny guide! Link to the sightseeing company: http://www.vikingsaga.no/daily_departure_sightseeing_oslo.shtml