I agree with Pete. I have been a certified diver for almost 20 years. The situational contrast between the ski holiday and the scuba holiday are very similar! The environments are comparable and the expense of the "sport" is somewhat comparable. Rentals are about the same, instruction is cheaper, but then you get to pay for the boat to take you out to the dive areas. But then there are the physical limitations- you can only get in so much bottom time per dive, before the technical conditions begin to get more involved. Very similar to challenging ones self to more difficult terrain.
At most beach resorts, a "recreational" syllabus is available to those not wanting serious diving, or for those just wanting a taste of the experience. That's how I was bitten by the scuba bug (along with a few friends and an ex- wife).
Generally, a "cert card" is required to rent equipment, as a liability cover for the rental shops.
But from the holiday standpoint, I think it's a reasonably close parallel. People go to beach resorts to relax, and then look for activities to participate in. Most have already heard of scuba diving, and think, hey- let's give it a try. From a physical stand point, beginning divers find it very easy. You breathe, you kick your feet, you keep your eyes open. EASY.
But to a beginner- it has many similar emotional challenges. Being under water challenges the psyche about the fear of drowning (compared to fear of heights or just being injured). Some get claustrophobic wearing the gear and the mask (sound similar to our gear?). To some, it's the fear of the unknown, the animals, etc.
But most of the fears are pre-conditioned by friends, TV, or movies. Can you remember "JAWS"? It did more to hurt the diving industry than anything else! Maybe in some cases, the current crop of ski movies out there do the same thing to our potential guests.
But the bottom line, IMHO, is that people want to have a vacation experience, with minimal physical effort, with maximal sensory inputs. To some, that's lying on a beach. To some of us, it's busting our butts for 6-7 days of all out Heli-skiing. It's the "lying on the beach/ cruise liner" set that we must reach.
The great question- "How do we encourage them to get off their butts, and doing something truly exhilarating?"