Crown Prince Frederik: What do we know about the next king of Denmark?

Crown Prince Frederik and his wife Princess Mary in 2018

Danes were given a surprise on New Year's Eve as Queen Margrethe II announced her abdication.

The world's only reigning queen and the longest-serving living monarch in Europe will step down on 14 January, which will be 52 years to the day since she became queen.

"I will leave the throne to my son, Crown Prince Frederik," she announced live on TV.

But what do we know about Denmark's soon-to-be king?

Crown Prince Frederik was known in Denmark as somewhat of a party prince in the early 1990s, but perceptions started to change after he graduated from Aarhus University in 1995 with a masters in political science. He was the first Danish royal to complete a university education.

During his studies he spent time at Harvard in the United States, where he enrolled under the pseudonym Frederik Henriksen.

He later served in the Danish navy, where he was nicknamed "Pingo" - which according to the Mail was earned after his wetsuit filled up with water during a scuba diving course and he had to waddle like a penguin.

The 55-year-old has earned his name as a daredevil, taking part in a four-month ski expedition across Greenland in 2000. He has been hospitalised in sledging and scooter accidents.

"I don't want to lock myself in a fortress. I want to be myself, a human being," he once said, insisting he would stick to that even after taking the throne.

Crown Prince Frederik took part in a 3,500 km journey across Greenland in 2000

Crown Prince Frederik, like Britain's King Charles III, is known for his passion for the environment. He has vowed to "guide the ship" of Denmark into the future.

His Australian-born wife, Princess Mary, grew up on the island of Tasmania and was working as a lawyer when the pair met in 2000, at a bar in Sydney during the Olympic Games.

She once said in an interview that she did not know he was the prince of Denmark when they met, saying: "Half an hour later someone came up to me and said, 'Do you know who these people are?'"

They are considered by some to represent modern values and have tried to give their four children - a daughter, son and twins - as normal an upbringing as possible, sending them mainly to state schools.

Crown Prince Frederik and Princess Mary attended the coronation of King Charles III in May

Unlike British royal tradition, there will be no formal crowning ceremony for Crown Prince Frederik. Instead, his accession will be announced from Christiansborg Palace in Copenhagen on the day.

He will become King of Denmark and head of state in the country - which is a constitutional monarchy - as well as in Greenland and the Faroe Islands.

Queen Margrethe II is the world's only reigning queen and the longest serving current monarch in Europe, taking the throne after the death of her father King Frederik IX in 1972.

The 83-year-old revealed the decision was made after a period of reflection following surgery on her back in early 2023.

"The surgery naturally gave rise to thinking about the future - whether the time had come to leave the responsibility to the next generation," she said.

"I have decided that now is the right time," she added, and offered her thanks to the Danish public for their support over the years.