My brother told me when I was seven that at the bottom of our swimming pool, where the filter cap was, that an invisible laser beam came out of it, aiming straight up. If you broke the beam, the bottom of the pool would open up and a shark would swim out. Whenever I went off the diving board I always jumped to the side to avoid the beam. I still do it to this day, without thinking about it.
A childhood belief about swimming pools

others believed things like this
- I used to think that a "pool shark" was an actual shark that lived in a swimming poolAnon
- I used to think that if you shone a flashlight beam onto a lightbulb long enough, it would eventually light.— Karen K
- i used to believe there were invisible sharks in the deep end of the pool, thanks to my older brother.— Melissa
- When i was younger,I used to believe i could see a shark in a pool .Anon
- 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