Can you add an option to disable an npc from floating in water?

That's been partially implemented in 1.9.0, however, I still have to figure out why they jump and therefore not dive in the water ...

@samolego any luck?

nope

@samolego I did a pull request

That's been partially implemented in 1.9.0, however, I still have to figure out why they jump and therefore not dive in the water ...

Try to override LivingEntity#isAffectedByFluids and return false value

Thanks!