There seems to be no distinction in height between things that are underwater and things that are swimming on the surface of the water. I don’t know why but my boats are getting randomly damaged and I think that I’m either crashing into things that are swimming “underneath” me or they’re temporarily able to hit it while I’m directly above them.
Should rivers, lakes, etc, gain a z level underneath their deep water tiles whose spaces are treated as “flooded” or a pure space of water? Which would require an oxygen source or gills to safely traverse in or the amount of time you have left in your character’s breath?
Would also be neat if there were several underwater z levels in order to simulate drops in underwater depths. It could add an interesting layer of underwater exploration and would allow more water-centric threats/options of progression. Perhaps even be a source of scrap, plastic, and even wood or salvageable machines that have sunken to the depths due to people pre-cataclysm carelessly dumping things in the river. Imagine building an underwater bases or labs you can only realistically reach with a divers suit or submarine that have a chance of being failed and flood or still functional and able to be traversed in normal gear once you take off your swim gear.