Re: AQUA LUNG or SNUBA????
Well, not to sound doom and gloom, but smoking raises the possibility that you could have congested areas in your lungs that could cause air trapping. If you ascend even from a relatively shallow dive, it's possible that the expanding air bubbles in your lungs' aveoli might not be able to release safely into your airway and rather could be driven back into the blood stream. From there they can end up in nasty places like the brain. This is an embolism, and is major bad news -- it can cause brain damage or death.
I see an occasional diver smoking out on the bow of a commercial dive boat, but I wouldn't smoke and dive. (But I know how hard it is to quit -- I did 17 years ago. ) If you really, really want to dive while you're still smoking, I'd have a diving-oriented doctor check you out first. And if you detect any wheezing at all when you take in a deep breath and exhale, don't dive!