Apparently the game doesn't care if you are above or below the water - if your XY coordinates are at least in the water area, it's enough to claim you are in (and sometimes even under) the water surface.
I've got completely soaked while standing on the pier (don't remember where exactly, approximately near Solnechniy) at 0.49, and then that experience repeated on the ship near Berezino at 0.50. While onboard of the ship I've changed my clothes to "fresh" ones several times, and in several seconds they too were becoming wet - while I was simply standing on the top floor of the ship.

More of it, when I accidentally fell from the bridge _on the ship_ and broke my legs, the game considered that I've gone prone _underwater_, so I've literally drown on the dry land =(