Large enough I am not faced with the reality of a corpse.

I don't see any corpses when I'm at the beach. I know they're out there in theory, but they're a distant enough concept I don't worry.

Great Lake sized lake with body on other side? Same.

A small lake/pond where I can see the area in which the corpse is floating? Perhaps even smell it? Or speak with a person who saw it? Hard pass.

Olympic sized pool? I can see the corpse. Hard pass.