Nice work Igor!
Any chance of getting a .hip file of the shark sim? Even without the shark animation in it I am interested to see the values you used on the custom VDB meshing as well as how it was rendered.
Are you using a shader on the water surface that splits between volume and mesh rendering of the water surface by a mask? If so are you using vorticity or velocity as mask values?
I like how you tried to do it all as a primary mesh without secondaries. It has a tidy look to it.
I saw your previous whale sim with the custom meshing and displacement speed ups using the FLIP surface attribute. Similar setup this time too?