Members of the royal families from across the continent including the Countess of Wessex gathered at a gala dinner to commemorate the milestone event at the Royal Palace in the Norwegian capital.
Guest of honour Sophie, 52, was the belle of the ball in a sweeping emerald gown, while Queen Sonja opted for an eye-catching lime green number, topped with a dazzling tiara, as they made their way to the Palace.
The Antarctic Peter I Island and the sub-Antarctic Bouvet Island are dependent territories and thus not considered part of the Kingdom.
Norway also lays claim to a section of Antarctica known as Queen Maud Land.
Currently there is just the 1 ferry company operating this ferry service, DFDS Seaways.
The crossing operates up to 7 times each week with sailing durations from around 17 hours 15 minutes.
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As Denmark's cultural hub, Copenhagen has many museums, galleries and music venues for visitors to enjoy.
But if you don't have a spare £1850 to spend on a new dress, recreate Sophie's regal look with the help of our edit below. Style yours with swept-up hair and a statement necklace and you'll look a million dollars.
The Copenhagen Oslo ferry route connects Denmark with Norway.
Sophie's dress is by Suzannah, and we love the forest green shade and dramatic ball gown shape.
The elegant simplicity of it is very beautiful, so if you've got a big event coming up then click (right) to invest now.