As a child, I was scared of a few things.
First among those things was open bodies of water. Yep, if the water wasn't enclosed and I couldn't see the bottom, there was no chance on the green earth I was dipping in my toe.
My fear stemmed from the completely irrational idea that a sea monster (think Jaws) would eat me. I know now, as I knew then, that the actual chance of being eaten by a sea monster is essentially zero. But that didn't matter; I was scared just the same.