I was playing earlier and found the zombies can now walk underwater without dying.
I was on the below server at the spawn point and got chased by a zombie, I ran out into the water and began swimming. I looked behind me and the zombie just started walking towards me and ended up below me because we were out a decent bit.
I swam around for a bit then went back to shore and it just followed me, then when it came back in (as it was going same speed as me) it just killed me.
Anymore info needed just ask and ill post.