Two schools of thought on that, both of them wrong. One idea is that Zombies can’t swim but they can walk or crawl underwater. Some suggest that they’re afraid of water and won’t cross. In some instances it’s been said that they won’t go over water even using a bridge.
So a fortified houseboat might be a good idea? Where can I get one of those depth charge launchers. LoL
I remember reading an old comic book from the 1940s in which a man is chased by zombies into the ocean because zombies can’t tolerate salt water.
They get him anyway because, at the mouth of the Amazon, where this story takes place, the fresh water displaces the salt water far out to sea so the zombies walk out in the fresh Amazon water and get him.