Safe compared to what? To never diving? To sitting on a couch? To playing golf? To mountain climbing? To jumping out of an airplane? To riding a motorbike along an unfamiliar mountain road on Koh Chang?

There's no simple 'Yes' or No' answer to this question but it is one that is asked all the time. Like the debate on many other difficult to answer questions, this one seems to be 90% semantics and personal philosophy (e.g., What do you mean by "safe"?), and only 10% about hard facts (e.g., data of accident rates in diving vs. other activities).

Let's start with the statement "Scuba diving is safe.  Why tell beginners otherwise?"  and start an debate . . . 

If you check your dictionary you'll find that 'safe = without risk'.  So can you say "Scuba diving is without risk."?  Of course not. However, for most people, safe and entirely risk free don't have exactly the same meaning. 

So you could say also that "Diving is safe, but it isn't risk free."? If it isn't risk free then some may argue it is unsafe.  Now, should we start telling would-be learners that diving is unsafe? 

Hang on, being unsafe also has a different meaning for most people than simply having risks involved.  But there are risks in everything we do in life, including washing the dishes or crossing the road. Take driving, for example, that's safe but not risk free and very few people would classify driving a car as unsafe. Diving is certainly safer than driving a car. Or is it? Can you prove that?

And so the argument goes on well in to the night . . . 

Whether or not semantics are a factor, its important that everyone  acknowledge important differences of opinion, and realize that the opinions and attitudes of the most experienced, i.e. the instructors, will affect newbie divers. 

The debate about safety has been going on since the sport of scuba diving began and will likely continue as long as people dive, perhaps because the sport attracts such a diverse group of people. Anyone attempting to answer the "Is scuba diving dangerous?" question will almost certainly be looking at the question from one particularly biased point of view. 

For example, a manufacturer of scuba gear would respond "Yes" but add a caveat "proper training and high quality equipment are required for safe diving."

A dive school, seeking to gain new customers would also answer "Yes" but go on to emphasize that anyone undertaking a course must be in good health and must follow the instructor's direction at all times. 

A doctor experienced in treating dive accident victims, might respond "No", scuba is not safe and that "you dive at your own risk." An accident victim or their family may respond likewise. 

A non-profit agency like the Divers Alert Network (DAN) might not respond directly but instead emphasize the importance of continuing research to understand the nature and causes of diving accidents, and on how to make the sport safer.

The comprehensive data collecting methods of the Divers Alert Network assure that most, if not all, scuba diving deaths and serious accidents are reported to it. According to DAN, about 100 Americans die while scuba diving each year. A large percentage of these deaths occurred when divers exceeded recreational guidelines, such as: diving deeper or longer than called for by dive tables; entering wrecks or caves without proper training or equipment; diving with medical illnesses which should have prohibited the dive.

In addition, DAN receives notice of approximately a thousand non-fatal diving injuries each year. Based on this information, scuba diving must be considered to present a finite, albeit small, danger to those who participate. 

Therefore, in the context of millions of recreational dives a year, the incidence of diving accidents and deaths is considered very small.

Comparing the amount of risk with other adventure sports (e.g., mountain climbing, snow skiing, bicycle riding) is difficult, if not impossible, for two reasons: 1) the true number of people actually participating in any popular sport is unknown, as is the frequency of their activity; and, 2) the nature of accidents varies from sport to sport, and any given injury can affect the victim to a varying (and unpredictable) degree. For example, breaking a leg on the ski slopes or suffering a concussion while bike riding cannot be meaningfully compared with a non-fatal case of the bends.

Similarly, comparing risks of scuba diving with essential but risky activities like driving a car is also difficult, since the number of miles driven, the type of driving, etc., are all unknown variables.

Anyone engaging in scuba diving must accept that the sport presents certain risks that aren't present if you simply stayed at home and watched TV.  Accepting this fact, the diver should understand that risks can be significantly minimized by such common sense steps as obtaining proper training, diving in good health, staying physically fit, adhering to established dive tables, and not participating in dives that exceed the limits of the individual's training.

At the end of the day it is up to the individual, through proper training and diving common sense, to minimize the risks to themselves.