" In my personal impression everything fades into blue/bluegreen very fast with distance and depth."
This is exactly correct. Water attenuates color over distance, sucking out red first, then green. This is why underwater photography looks the way it does. Add in the murk to add depth and you'll quickly get something that feels like you're under the ocean.
The reason I was saying this seems possible now in TG is because of the render layers. Breaking out a render into component layers and using the depth passes as matte layers to remove the red channel over the depth of the matte and in similar but lesser amount to the green channel will instantly add a lot more realism.
I've included a screen grab from one of the spots here, though this still really doesn't do it justice. The moving frames display it all much better
