Both images are from an identical setup. Just TIR turned on for the lower one. The water has zero reflection, so all comes just from TIR. I guess this is the kinda thing it was designed for. I was only playing with caustics. Amazing what you can find when just playing around

i forgot who or where or when, but there was a decent tut up somewhere about TIR. It's a useful tool. Certainly adds realism. The thing that annoys me about water planes is that it doesn't actually 'FILL' the scene with water, but merely ads a infinite 2D plane of it. It shouldn't be done with cubes or whatever. drac

Yeah, I ended up writing the whole physical background of tir. Basically, it's when the angle of light or los in bryce's case exiting the refractive material is shallow enough so that the resultant refraction (n) of the material causes the final angle of the light/los to be less than the 'escape angle' from the water. Thus it reflects back down like in the image above. Jewlers use this law of nature when calculating the suitable angles for diamons as to throw the light that comes in from all angles out of the top crown thus producing a sparkling/lit effect.

Just curious... what was the render time difference between the images?

From what I remember, there really wasn't a great deal in it.