The children were playing on the inflatable castle.

孩子们在充气城堡上玩。

《柯林斯英汉双解大词典》

To celebrate, their grandparents had set up a tent and an inflatable bouncing castle in their garden and, in true German fashion, long tables groaning with no fewer than seven homemade cakes.

WSJ: The Cake That Steals the Party

As much as we wish this was some type of anti-gravity bouncy castle, NASA's current experiments with inflatable structures are intended for slightly less entertaining implementation on the moon, where crews will use them as outposts for research, testing, storage, and living.

ENGADGET: NASA develops inflatable lunar habitat