William and Kate release new photos and video of their 3 kids

The Duchess of Cambridgehas released new pictures and video of her family playing in a woodland wilderness garden she designed for London's Chelsea Flower Show.

Co-created with landscape artists Andre Davies and Adam White, Kate's "Back to Nature Garden" includes a rope swing, a tree house and a stream with waterfalls.

Her office said Kate, wife of Prince William, the Duke of Cambridge, has beena strong advocate in the mental and physical benefits that nature and the outdoors had on children and adults alike.

"It's a natural space, a really exciting space, for kids and adults alike to share and explore," she told broadcasters ahead of the opening of the garden on Monday.

"I really feel that nature, being interactive outdoors has huge benefits on physical and mental well-being particularly for young kiddies," Kate said.

In a video posted on their Instagram account, the couple's three childrenGeorge, Charlotte and Louiscan be seen playing on the swing, by a wooden den, and scrambling barefoot through a stream. Louis, who celebrated his first birthday last month, can be seen walking for the first time and waving a stick.

Kate said she had been focusing on early childhood development in her recent charity work.

"I believe that spending time outdoors when we are young can play a role in laying the foundations for children to become happy, healthy adults," she said.

The Chelsea Flower Show, open to the media and guests on Monday and to the public from Tuesday to Saturday, is the most prestigious event in Britain's gardening calendar.