When I was about three, Southern Bell (one of the phone companies) had this commercial with an announcer guy and a woman at a hotel pool. The woman dove in and the announcer pulled this string and sharks came out of this holding cell, and the woman managed to get out in enough time. Because of that, I believed that there were sharks in a bin at every swimming pool, so a few months later when I started taking swimming lessons at the YMCA, I dove in the pool to go look for the sharks myself and was very mad when the instructors found me and wouldn't let me swim the rest of the day.
A childhood belief about swimming pools

others believed things like this
- i used to believe there were invisible sharks in the deep end of the pool, thanks to my older brother.— Melissa
- I used to think that a "pool shark" was an actual shark that lived in a swimming poolAnon
- I believed that the ladder on the back of a trailer/rv led up to a swimming pool.— marilese
- Up until I was in 3rd grade I believed my bathing cap is what kept me afloat in the swimming pool! Anon
- I used to believe that if you farted while swimming in the pool, it could propel you foward really fast.— Rick
- When I was a kid I used to think the "carpool lane" was an actual pool cars went swimming in— skeez