Saje, I just wanted to explain to you that with my Newfoundland dogs not being able to swim has nothing to do with their not being introduced to water properly. These dogs are bred for the show ring, not for proper behavior conformation, the conformation of my dogs is completely wrong for swimming. These dogs are big, poofy and are being bred more for being pretty rather than being proper for their job. My dogs with the conformation they have would most likely drown from the excess coat.
I have had Newf's in the past (a few years ago), which I used to partake in water rescue with, we had fun with it. I have owned Newfoundland dogs for the past 25 years and I have found a big difference in the way they are being bred.
Just by reading a book on dog breeds is in no way a true reference to the breed. Some breeds the breed clubs try to continue breeding for behavioral conformation, where some other breed clubs are breeding only for a fantasy pretty conformation...whatever is winning in the show rings. Unfortunately the Newfoundland dog breed is suffering right now, unless you get a Newf from someone who is still breeding for the proper conformation the chances of your getting a Newf that cannot swim is pretty high.
For myself, my rescues and mongrels have been my best swimming buddies. I would suggest anyone wanting a good swimming companion to go to your local rescue and get a retriever mix, poodle mix or a Newf mix.