Fighting Zombies in a Swamp

Swamps are the location for a lot of horror stories and RPG adventures, and they often come populated with zombies. Of course, once adventurers gain enough experience they begin fearing zombies a lot less, even in relatively huge numbers. But it seems to me that too rarely are the possibilities and implications of fighting undead in a swamp really used to their full potential…

Imagine tough adventurers with swamp water up to their waist, fighting off zombies. What if the zombies, instead of trying to bite, claw or swing crudely with their weapon, were instructed instead by their creator to form groups and grapple adventurers, dragging them under the swamp water where they can’t breathe (Something the undead don’t need to do) and holding them there? If an adventurer is dragged down into the water with his torch or lantern, it would also mean less illumination for the living. And sure, one zombie might have trouble grappling an energetic adventurer, but five zombies grappling at the same time?

— Fighting Zombies in the Swamps!!! What a Drag… – Eye Ray of the Beholder