If you are considering SCUBA diving, just do it. After you have naturalized the basic skills of diving and are looking for something more to do while diving, consider diving shipwrecks. Shipwrecks are virtually everywhere, but some of the most thrilling around the US that require only intermediate diving skills are 5 - 30 miles off the east coast. The best reference book we've used to find wrecks locations and their history is titled: "Graveyard of the Atlantic". Most of the wrecks are in 60 to 140 feet of water. Visibility during our most active diving era (1983-1995) was often over 100-200 feet.
I have over 200 hours of underwater video from that time, most of which I've never even reviewed, but I'll eventually put together a clip or two of some of the better shipwreck dives off the east coast. Most of the video was shot on equipment prior to Sony's Hi-8 technology but is good enough quality to effectively share experiences.
We still dive, but after we lost most of our best dive gear during the infamous shipwreck of the once renowned "Little Cayman Diver" liveaboard charter, we never replaced it. We were now married with near future baby plans and our adventure agenda was winding down for a while anyway.
Now we've since pretty much succumbed to our mid-life mode of only choosing easy diving in warm salt-water where the dive boat provides everything, slaps the gear on your back, checks your air flow, and pushes you overboard in places like Hawaii, Florida, Mexico, and the Virgin Islands. However, our thirteen-year old is now quite the openwater snorkeler, sea-life knowledgeable, and is at a SCUBA certifiable age.... so stay tuned, the cycle could repeat for the next generation of adventure-seeking offspring...and my how diving gadget technology has improved... :)