It’s quite common to have a fear of open ocean swimming, whether irrational or not.
I do it, but I get freaked out every once in a while.
I saw Jaws when I was 6, totally scared the shit out of me.
Only The Shining was worse for me as a kid.
Scared me, and I was 26 in 1976. Roomie flung a box of popcorn up in the air when Ben Gardner’s head popped out of the boat hull.