I'm an instructor for the Handicapped Scuba Asssociation Intl. (HSAI)...and very definately a paraplegic can dive and dive very well.
My training with HSAI was quite extensive. We had to be both student and teacher. They bound our legs to simulate para or quad or amputee. It's amazing how much propulsion you can get just using you arms efficiently. We were taught to work with, paraplegia, quadraplegia, amputee, blindness and deafness.
Deafness I consider the hardest to teach-with lip reading most people only "hear" 30% of what's been said.
Blind diving was the most difficult skill for me, I couldn't tell where I was in the water column. Communication is all tactile.
We had extensive class training in the nature of various disabilities...In the case of a para, many use a catheter. I lot of consideration has to given in the wetsuit and boots area. With no feeling it is easy to damage a foot just putting on the equipment. Special care has to given with the environmental area, sun burn...overheating, getting too cold etc.
HSAI gets around the basic abilities issue by issuing 3 levels of certification. First level, the diver can perform all the skills that an able diver can perform including rescues. The 2nd level is where skills such as rescue cannot be performed...this requires a 3 person buddy team...2 able bodied. The 3rd level is issued when the diver requires assistance in the most basic skills (quad). This requires that both buddies have HSAI traing.
Check my website out:
www.cbscubaodyssey.com
On the lead page click on the HSAI icon