Princess Mary steps out with her family at Gråsten Palace

Princess Mary has stepped out with her family for one of the most popular events of the Danish summer.

And her four children appear to have grown remarkably since they were last seen in public.

Prince Christian, who is turning 13 later this year, is nearly as tall as his mother, while Princess Isabella, 11, isn't far behind.

The young princess looks like a mini-Mary, wearing a long skirt paired with a plain t-shirt –taking style cues from her mum who frequently dresses in similar outfits.

The appearance by the royals is an annual event outside their summer residence, Gråsten Palace, in southern Denmark.

Around 300 horse riders pass by the royals, who receive and meet many of the participants.

The Australian-born Crown Princess was seen taking poesys of flowers from the riders, and patting the horses before they continued in the parade.

The royals later shared a photo of the many flowers they'd received.

Mary is a keen horse rider and is frequently seen on horseback on the grounds of their palaces.

Twins Prince Vincent and Princess Josephine, seven, were also at today's event along with their pet border collie, Grace.

Their dad, Prince Frederik, was dressed in shorts for the warm Danish weather. The Crown Prince turned 50 in May with thousands of people turning out across the country for a series of events to mark the occasion.

It's been a tough year for the Danish royals, after Queen Margrethe's husband, Prince Henrik, died in February following a lung infection.

The 83-year-old had previously been diagnosed with dementia.