What's happening with the terrains is that the rays are penetrating the terrain, and then hitting and penetrating the water plane as well. In these areas you're seeing the dual-material effects of this, and perhaps that's what's buggin ya? One way to get rid of this dual-material effect is to lower the Ray Depth to "2" in the Render Options. This means that the data rays will hit the surface and bounce one other time after the initial hit, and thus still pick up any wave-related reflections. Which is why you'd lower it to "2", instead of "1". "1" will give you black "null reflections", which are unacceptable. You can see the results in these two renders. It is the same scene, only the Ray Depth and TIR depth were lowered in the second image. I purposely didn't let the first, standard image finish rendering, as it was pointless. Just a simple workaround for you, Shaddex! Flawed in some ways, but it will also decrease your render times when working with reflective waters. Don't bother using it with refractive waters (like if you have a sand plane below your waters), as most anything underneath the water will not be rendered at all... Hope this helps.