Going Underwater (Realtime Voxel Physics Engine) 

Added a third geometry pass to render the backfaces of the particles, so you can now see the surface of the water when submerged. This still has a pretty low cost to render on the GPU. I will try to bring over things from the volumetric lighting experiments (e.g. godrays) while keeping things visible underwater. It would be cool to have some more plant and animal life in the water that might have higher poly counts and maybe use instancing/mesh shaders for that. I will work on adding settings so you can play from low-end portable to high-end PC.