This is the version our father [Camden Road London Scouts] taught us:
   
Sammy was a sailor, a sailor big and bold
Shipped aboard a whaler and tumbled overboard.
He shouted someone save me, but someone said go hang,
The sharks are swimming round you so his shipmates sang:

Oh! Swim Sam swim Sam swim Sam, show them Sam you're a swimmer
Swim like a snow white swan,
Sam you know how a snow white swan swims,
Six sharks shivering sharks, are going to snap your limb,
So a swim well swam is a well swum swim,
So swim Sam swim Sam Swim!