Hey, I think that is technically expected when you have 0 opacity. We have to use the opacity for the reflections and the lighting if I am not mistaken.
I am not sure what exactly is going on in your other images. It almost looks like it is not able to trace far enough into the scene to capture the sky at some angles. Out of curiosity how deep is the opaque surface under the water? If you put a straight opaque material directly under the water does it make a difference?
I am linking Brian Karis to thsi thread since he wrote the SSR on Translucency.
I tried to make a plane right under the water now, but nothing happened. However, I started a blank project, imported the same landscape, made sure to add exponetial height fog, atmospheric fog, skylight - and pretty much the same setup as in my original project. And now it works fine!?
I also added a fresnel in the opacity, which gave almost the same result as in the vRay example =) It would be cool to have a checkbox for this in the future though
