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

Bring her along on your diving trips -- maybe she doesn't like it because she doesn't understand it. Let her witness firsthand why you're passionate about diving and if she wants, you guys can sign up for one of those couples diving classes together. If she doesn't, she can always spend time on the beach or boat and suntan while you dive ☺ after that, you can treat her to dinner and promise to accompany her to do something she loves next time round.