I have added grid lines to show where tiles end, but these are basically the water edge tiles used in Factorio. They are between 60% to 90% water, although these tiles are regarded by the game as ground - you can walk on them, you can plant entities on them, etc.
This is very confusing, especially for new players, who believe they can't build entities somewhere, then discover they can.
I suggest a graphical only fix, to make these tiles be about 60%-80% ground, to make it more clear that they are indeed ground tiles, and not water tiles.