Diving is safe, but it is not risk free. You should not tell students starting a course that diving is unsafe, since that is not true. We are obligated to explain the risks involved. Yes, but there are risks in everything we do in life, including just sitting still or sleeping. Take driving, for example.
Diving is certainly safer than driving a car.
Driving is definitely not safe. This is not idle chit chat, since the debaters are all instructors who teach scuba, and who can be expected to impart their feelings to open water students. Whether or not semantics is a factor, we must acknowledge important differences of opinion, and realize that the opinions and attitudes of the most experienced will affect newcomers to scuba diving. In addition, the divers had much more degenerated intervertebral disc disease than the non-divers. Unexplainedly, there was no statistically significant correlation between occurrence of bright spots and years of diving experience, or with the number, mean duration or depth of the dives.