Water proof zipper?

Question:Is there a such thing?

If there is, is it expensive to manufacture?

Do you know any websites or links for me to get more information on the water proof zipper?

And on what materials is it used?

Answers:
Some "Dry Suits", underwater diving suits & rescue suits have waterproof zippers on them. The suits are usually made of neoprene or compressed neoprene.
If you do a search for "dry suits' you'll see what I mean.
Hope this helps.