Diving is my passion and I talk to people about it all the time. I especially get questions on vacations, when folks see a dive shirt or see me coming back off the boat. They have generally tried snorkeling and like it, but aren't sure about diving...especially not sure about sharks. I love sharks and I think my excitement sets them at ease a bit about a possible encounter. I also share with them a bit of the peril that sharks face - after all, as divers, we also have a responsibility toward conservation and stewardship, and learning that sharks are threatened starts a transition from man-eater fear towards compassion.
I always recommend that people try a discover scuba diving intro. If doing it at a destination, they will be able to spend some time in the pool to get ready and then experience diving in the ocean. If they are inland (home for me), I still recommend trying the discover so that they understand what it's like to have on the gear and can experience weightlessness and three dimensional freedom for themselves.
I have had several people that tried the discover and loved it. Many have gone on become certified.