I used to believe that the water in the swimming pool of a cruise ship was actually the ocean water. I thought that the only thing "keeping the people in the pool" was wire or mesh.
A childhood belief about swimming pools

others believed things like this
- I used to believe that your tap water came from the swimmimg pool.— Mimi
- I used to think that a "pool shark" was an actual shark that lived in a swimming poolAnon
- When I was little, my dad told me that if you pee in the pool the water will turn purpleAnon
- I believed that the ladder on the back of a trailer/rv led up to a swimming pool.— marilese
- I used to believe that if you farted while swimming in the pool, it could propel you foward really fast.— Rick
- Up until I was in 3rd grade I believed my bathing cap is what kept me afloat in the swimming pool! Anon