partially baked lighting, and fully baked lighting
This is kind of unrelated, but I have been experimenting with baking out caustic lightmaps in UE4 and then computing bounce lighting. You can see it add the bounce lighting over time. Each time it resets it is calculating another bounce and accumulating them.
The bounce lighting does not actually have shadowcasting yet, only shadows at the water surface are calculated. To support shadowing for bounce I would need to add some kind of iterative ray marching or use a totally different approach. Would like to experiment with that soon.
@RyanB Those caustics are delicious! I see what looks like a bit of foam generation in the works to the right as well. Now you just need a shoreline effect and oh my… Anything that gets better looking water in UE4 is fine by me.
Awesome! I want caustics ever since I saw them being used in Assassins Creed Unity where metallic objects would cast a caustic pattern on to the environment. I hope lightmass gets an upgrade! 
May be Support GPU render? , GPU render very fast. If can be support CPU+GPU … it’s a new world.