Sinking

I love the swirling lights you've created from the characters eyes. Also, because the eye area itself has been colored entirely black, it adds to the feeling of detachment and the depth of the water. That wonderful pose, the fact that it's not directly side-on or straight forward with the body bent, is much more dynamic - as is the nature of water. I also love that you've showed that the water exerts itself on the ears. In addition, the blur that you've added around the character also emphasize that submersed feeling.

What would help the piece even more is to add a slight gradient. But that depends on just how deep the scene is. (ex. not from a super light blue to dark blue, but a dark blue to a very dark blue or even black.) Like the lights of the eyes, it would be nice to see that wonderful tail curve a little more and the fur to stick up more towards where the surface would be (which is an effect of both buoyancy and gravity.

The composition is great and some more bubbles or light shafts would be a nice touch, but they are only cosmetic effects.

In conclusion, this is an impactful piece of art that clearly conveys its message. Nice work!