What about people that couldn't swim before they were infected? Would they just automatically learn the ability to swim? Or are the zombies just not buoyant at all?
MHI advises the liberal application of shotgun at close range - decapitation plus skull crush all at once. Decapitation by machete will also work if you crush the skull after. The animated corpse doesnt swim per se - it will sink (Dead weight, right?) and can then walk under water, but the dismembered pieces will float like traditional road kill once they are de-animated.
For a more in-depth review, I highly recommend Larry Corriea's Monster Hunter International and Monster Hunter: Vendetta. Monster Hunter: Alpha is out in September. I got Jarhead to read these and he gave them serious thumbs up.
Who says you have to read non-fiction to learn anything new!!