The only real 'career' in scuba diving is working as a dive master or instructor or similar - for which you most definitely don't need a college degree and unless you plan to own your own dive centre any degree you do have will be almost immaterial in many locations in terms of getting a job. Degrees that might help include business studies of some description, but if you want to work in the industry full time then you need languages - a degree in German would get you a job where I work by the end of today!
Other fields such as marine biology, underwater archeology, search and recovery (police, army, coastguard) etc. are fields in which you will do some scuba diving, but as a means to an end, rather than an end in itself. As BioLogic suggested above - you'll do a few dives and spend the rest of your day sifting through whatever it is you are researching at the time.
Possibly you will be sitting in 5 metres of zero vis and sewage looking for rotting corpses. Depending on the field, you may find this rather takes the fun out of the diving itself.
Underwater photography and videography can be good earners so some form of study along those lines might be worth considering. There are niche market careers available in tec diving but you will pay a great deal to get there and it's not for everybody.
Commercial diving and scuba diving have very little in common apart from the fact they occur underwater and involve breathing compressed gas. The commercial market can be very lucrative, but also can be hard and dangerous work. Usually the trade (cutting, welding etc.) comes before the diving - ie better to be a welder trained as a diver than a diver trained as a welder.
Hope that gives you some ideas!
Crowley