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》

The inflatable plastic container looks like a red "castle" with elements of Suzhou gardens, Buddhist temples, European porches and columns.

中瑞城市项目“容器”是一个外观呈红色的充气“城堡”，既有中国庙宇裙摆式的屋檐、苏州园林风格的围墙，又有欧式的门柱和走廊。

youdao

Sell inflatable arch, model, bouncer, slide, castle, cartoon toy.

销售充气拱门，模型，保镖，滑梯，城堡，卡通玩具。

youdao

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