Thank you, folks!
I enabled soft shadows and updated this a few minutes ago, too.
The fish shadows were very hard considering how far away some of them were from their shadows.
I love the light-playing across the terrain beneath the Sun, when turning from the dark side towards the light it looks really good when the bright areas come into view, I think it does, at least.
The 'caustics' hitting the ground are from the actual rays this time, not from my old method of making procedural caustics as a surface layer, these ones actually cast from the light rays perfectly.
Cheers!
Done.