Prince George, Princess Charlotte and Prince Louis had a whale of a time during a sneak peek of Kate's stunning garden at the Royal Horticultural Society's Chelsea Flower Show.
The Duchess of Cambridge will unveil her woodland wilderness garden - which aims to encourage children to spend more time outdoors - at the event in London this week.
A barefoot George and Charlotte were seen dangling their legs over a stream, while an excited Louis ran along a wooden path carrying a branch as the Duke of Cambridge looked on smiling.
Four-year-old Charlotte, dressed in a floral frock, and one-year-old Louis, wearing shorts and a cardigan, could be seen trying out a swing seat which Kate has already been photographed on in the build-up to this week's show.
Five-year-old George could be seen adventurously clambering across the stream.