You fall deeper and deeper into the water, kelp tangling around your legs as you struggled to return to the surface. You're holding your breath as best you can, kicking and trying to swim. You can't tell if it's water or slime entering your lungs, vision blurry. Is your mouth actually lengthening, or is it an air-deprived hallucination?
Maybe the claws you see are just... not really there... Though suddenly being able to breathe again must not be something all in your head. The fins replacing your ears isn't in your head either, you don't think, because you can feel them move, feel the scales spreading across your body and tail tearing out of your tailbone.
You've never been a good swimmer, but this somehow feels right and natural, the darkness falling away around you.