Duchess of Cambridge Kate Middleton probably had the best royal outing ever when she visited the Scouts’ headquarters in London, England, on Thursday, March 28. The mom-of-three got to play with the 4-year-old and 5-year-old kids there when she ran into the nearby woods with them and playfully crawled into a small den with a little girl who was pleased to be spending time with the duchess.

“It’s very waterproof in here,” Kate, 37, joked about the small den which was built by the youngest Scouts. Frankii Newbury, the early year’s pilot project leader, noted how well Kate got along with the children at the park. “[Kate] got straight in there with one of our Beavers and checked it out. It was wonderful and the Scouts absolutely loved her. The highlight was the duchess, smack bang in the middle of it all, getting in a den — braver woman than I am,” he said.

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Apparently, the Scouts did a number of tests to see if the den was actually waterproof before the duchess arrived to meet them. “Three trials were dry, one was wet!” Frankii explained. “We are very proud that it was three quarters there.”

Scroll below to see more pics of Kate’s fun outing with the Scouts!