I like to go diving, but my wife doesn't like it, although it's only for the weekends. How do i convince her?

Any specific reason she does not like it? I agree with @yuna, get her to try it out once. It will give her a new perspective. I would not recommend you to stop diving just because your wife does not like it (try till you succeed :D). Diving is something beautiful and cannot be explained unless experienced firsthand.