To add to this. Any source that can be used for fishing, has no height limit for interacting with it.
So filling a water bottle, or casting out your line, can be done as long as you're above it.
Though fishing can't be done too far out into the ocean, so attempting to do it from a scripted properties interior failed, but water bottles don't seem to have a limit to how far out they can be used at, and as long as the wall and floor ends meet, it thinks you're directly above the water and will allow you to refill your bottle through the wall.
If it's possible to set a height limit, that'd work, or just making it so it cant fill that far out would work too, because as far as I know, it's the only kind of property that exists over water like that.