You sink into the water, and even if you try to hold your breath, you cannot do so forever. Yet the water, when it enters your lungs, feels heavier and slimier, and somehow doesn't hurt. In fact, somehow you can still breathe, even as your attempts to swim higher are weak. You manage to reach the surface though, gripping onto the edge desperately.
Or.. is it you? Those don't look like hands, more like webbed paws, and if you go cross eyed you find a forming muzzle of some sort. Your legs are already almost fully fused into a tail- you won't be needing those any time soon after all- which twists with your attempts at movement. It is you, just, you suppose, a no longer human you.