I tried using the wavy sea thing underneath the transparent water of Pats but it really doesn't show up at all. I should reload that model & see how it looks without the water - use empty space instead…
The following screenshot uses a 4x4 model set at [x=0,y=1.9,z=0] - water y range goes from -2 at floor to -.2 at surface.
It looks OK set at y=-.25 as it avoids the unsightly walls rising from the water floor to the water surface but then becomes an issue if you want fish. Were there a transparency option with textures this would be great but until that option is included in any future release this is probably the best solution. A workaround would be to model a surface to the walls & texture them appropriately though this might be a little more timeconsuming & not practical for the regular level creator.
The other thing to note is that, ideally, any texture used would need to be seemless. This one here fits quite well as it is the water surface itself only enlarged 4 times which you would have already downloaded.
I also left the bottom right corner free so you could see the difference. On other level styles, it does make a more noticeable improvement.
Something more to play with. All files included here.
Robbie

PS oh & the other thing to consider on this initial model obviously is that any incorporation into levels needs to consider the deadspot currently at the centre…
PPS the AC3D file probably wasn't worth adding but it's here anyway - just a 4x4 rectangle located at 0,-1.9,0
