I was riding a horse, and it fell into water 3 blocks deep.
What I expected to happen was: The horse would float to the surface of the water and continue on.
What actually happened was: The horse did not come back up, and it drowned to death.
To reproduce: Break and saddle a horse and ride it into water that is at least is three blocks deep.
This is annoying in both survival and creative as I have to find and train another horse. This does relate to an issue stating horses kick you off in water deeper than one block. This also affects all the versions after 13w16a.