This WIP is animated, but cannot be efficiently presented as a GIF. Check out the video in the attachments or on Discord to see it in motion.
I've now started work on the underwater environment for the Vaporeon piece. Here's a very early look with just the sand floor and animated kelp in place.
The second image shows the overall structure I'm going for, instancing the kelp in a ring around the scene. I've also experimented with god rays (third image), but need to refine that a little more to make it work.