Frederik and Mary's blue-eyed brood looked to be enjoying their carefree summer break in each other's company.
The eldest of the four children Prince Christian embraced his role as big brother and pulled his little twin siblings Prince Vincent and Princess Josephine in a truck around the garden while Princess Isabella led the way.
Sisters-in-law Crown Princess Mary and Princess Marie, with their glossy brunette tresses in semi-updos, were the epitome of summer chic in floaty dresses.
Mother-of-four Princess Mary looked like she might have taken a leaf out of new mum Kate Middleton's style book as she wore a navy blue dress, wedge sandals and oversized sunglasses.
The male members of the family had coordinated their summer look in vibrant polo shirts.
Completing the happy scene in the beautiful palace grounds were grandparents Queen Margrethe and Prince Henrik who looked on at the little heirs and heiress.
Haakon kicked off the festivities in style by arriving at Skaugum Palace via parachute before enjoying a two-day festival themed party with his family and friends.
Live music, including a performance from Prince Haakon himself, was the event's highlight and when the royal took to the stage with his sister, Princess Märtha Louise, he thanked the host of artists and performers making the occasion so special.
Inbetween the weekend's event Haakon and Mette-Marit showed that they are just as much in love as ever, holding hands and sharing several kisses as enjoyed the company of their friends and family.
With the exception of Haakon's parents , King Harald and Queen Sonja who stayed in their summer residence, Bygdo Kongsgård, all the guests stayed in tents set up in the palace's grounds.