How long do pigs get?

I have never heard of animals called Sea Pigs. Pig boats is a more or less derisive term for submarines, and was applied to Italian Mini-subs in this role. the story is the shape of the hull resembled a pig, and get this storage sheds on some Italian Pig Farms were used to conceal the craft before they were deployed. Pig Boat is a derisive term for submarine.