I'll follow up on what Waterdogs said; that there is a whole universe of things to learn in Scuba: oceanography, physics, physiology, icthyology, conservation, navagation, geology, etc. You don't have to be a career scientist in any of these fields, but you get exposure to all of them when you start learning the sport. And you can follow up on whichever of them stimulates your interest most.
Diving can be done locally, but also generates opportunities for travel. Would your wife go along to the Bahamas, Fiji, the Caymans & just shop & snorkel while you dive with others on your tour boat? She will know where you are when you leave the house in the morning with a gear bag. You meet nice people there, & they sometimes have non-diving wives that hang out together when the guys go on a weekend & take the ladies along.
Most of my co-workers were non-divers when I took my Master Diver class, but every Monday, a group showed up at my desk to hear about my marvelous adventures in the surf zone. Some of them got certified based on what they heard. Curious types just never get tired of exploring the underwater world, & you always have a great topic to discuss at parties.
Surely, if you were on a paintball board, the enthusiasm of those players would sell their sport with equal enthusiasm. I hope that hearing our side gives you an idea if this is worth checking out.