Ferries from the UK to Norway
No ferry sails from Britain to Norway. Scheduled passenger services to Norwegian ports leave from Denmark, Sweden and Germany only, and no operator currently runs the North Sea direct. Anyone going by sea therefore books two separate legs: a crossing to the continent, and a second crossing into Norway.
Through the Netherlands to Hirtshals
Stena Line runs Harwich to Hook of Holland up to four times a day, from 6 hours 30 minutes. Further north, DFDS leaves Newcastle for IJmuiden at 17:00 daily and arrives after about 16 hours 45 minutes, which converts the crossing into a night's sleep instead of a lost day. Both landfalls leave a long day at the wheel before Hirtshals, the Danish cape where nearly all Norwegian traffic starts.
The second leg follows the destination rather than the fare. Color Line's SuperSpeed ships reach Kristiansand in 3 hours 15 minutes and Larvik in 3 hours 45 minutes, the shortest hops into southern Norway. Fjord Line serves Kristiansand year round in 3 hours 55 minutes and, from March to September, in 2 hours 25 minutes on the Fjord FSTR catamaran. For the west coast one sailing stands apart: Fjord Line leaves Hirtshals at 19:15, calls at Stavanger at 07:00 and berths in Bergen at 13:00, roughly 17 and a half hours, and it saves the mountain drive from the Oslofjord.
Through Germany, if Oslo is the target
Color Line's Kiel to Oslo ship departs at 14:00 every day and ties up at 10:00 the next morning, a little under 20 hours. One overnight passage replaces both the run up Jutland and the Skagerrak crossing, which makes it the shorter chain for eastern Norway and the calmer one with children or a caravan on board. The price is the drive across the Netherlands and northern Germany to Kiel, plus a cabin fare on a cruise ferry rather than a seat on a fast craft.
Travelling without a car
For foot passengers the Kiel route is the spine of the journey: Kiel sits on the German rail network, and the ship ends the trip in Oslo itself rather than at a Danish terminal. Hirtshals is the opposite case, awkward to reach and awkward to leave without a vehicle, so the Danish chain rewards drivers and penalises everyone else. The full Danish picture is set out under ferries from Denmark to Norway.
When flying is the better answer
Two sea crossings, two fares and a long day of driving between them pay off when the car is the point of the trip: hiking kit, a caravan, a dog, or an itinerary that needs wheels once you land. For a city break in Oslo or Bergen, or for any trip under about ten days, the aircraft wins on time and usually on cost, and the ferry chain is worth keeping for the outward leg of a longer tour.