Thank you for your efforts in writing this package. But queries arise:
In this render I set the PM:Half Distance to 5 feet, but details can be seen much further away. In my experience in low-visibilty-range British sea scuba diving, I see the visibility limit as a blurred opaque wall at a set distance L, which is the visibility range. I tried resetting the PM:Scatter Value, but likely in the render the light is scattered only by objects declared as props and characters; but in real sea the light in passage through water (including light which has already hit an object) is also scattered by millions or billions of silt particles and/or plankton organisms; likely the visibility limit "wall" is where the nearest large solid object is so far away that nearly all lines of sight from the camera hit first a silt particle or a plankton organism. To make this scene, I went into one of my previously-made underwater scenes, parented all props and characters to one character, and saved that character "with all child characters and props" to library, so I could load the whole setup bodily into a run of UnderWaterScene.pz3 .

As regards underwater optics, I have noticed on land that at night, lit only by monochrome sodium lights, I can yet see green leaves as green. I suspect that plant chlorophyll (including in green phytoplankton) actively emits green light as it absorbs blue and yellow and red light.

For me, the "depth cued" would be useful, if I could set the depth cue color, if I could make depth cuing also happen on rendering, if I could set the maximum distance rather than it being automatically set at the mesh vertex farthest from the current camera.