Prince Nikolai Of Denmark Celebrates His 18th Birthday At The Royal Ship Dannebrog [Getty Images]

COPENHAGEN, DENMARK - AUGUST 28: (L-R) Princess Isabella of Denmark, Princess Josephine of Denmark, Crown princess Mary of Denmark, Prince Vincent of Denmark and Prince Christian of Denmark attend the 18th birthday celebration of Prince Nikolai at royal ship Dannebrog on August 28, 2017 in Copenhagen, Denmark. (Photo by Patrick van Katwijk/Getty Images)

Getty Images Entertainment Patrick van Katwijk