This completely depends on the zombie in question. I think that the answer to this question is the same as the answer for Why does a dead body float in water?. read more
Zombies don't exactly have the motor skills that we do. They can barely walk, no way could they swim. Brooks made a big deal of their ability to walk on the ocean floor and I believe he estimated several million were still wandering around in the ocean after the end of WWZ. read more
Update: obviously miyah doesn't have a life either if she's just going to say stupid things like that. read more