Some added thoughts about labeling ...
Sometimes a term is very clear-cut for the type of dive, while other times, not so much. If we look at the various filing cabinet terms for the types of divers, often these are:
1. Military
2. Commercial
3. Scientific
4. Sport/Recreational
5. Public Safety
These can be divided into sub-groups:
1. Military
A. Combat - such as Spec Ops
B. Salvage - such as Navy hard-hat divers
C. Rescue - such as rescue swimmers
2. Commercial
A. Offshore - such as an oil rig diver
B. Inland - such as a bridge inspection diver
C. Saturation - including the use of hydrogen gas mixtures
D. Heavy - such as surface-supplied hard hat
E. Light - such as a hull scrubbing diver with either open circuit or hookah
F. Governmentally legislated - such as a pro U/W photographer who needs an HSE Class IV ticket in the United Kingdom
3. Scientific
- I can't really think of ways in which this group of divers breaks itself down since all the scientific divers I know are more interested in the work they do rather than by the tools they use. Rather than divide themselves by open circuit, rebreather, submersible divers, my experience is they are:
A. Biologists
B. Geologists
C. Oceanographers
- Biologists may break themselves into such groups as ichthyologists or zoologists and so forth
Perhaps Thal can add something to this?
4. Sport/Recreational
A. Freediving & Snorkeling
B. Recreational Scuba
C. Technical Scuba
D. Professional
4. Public Safety
A. Police - such as a underwater crime investigator
B. Fire - such as a volunteer FD rescue team
C. IUCRR - cave rescue & recovery
D. SRT - such as a SWAT team
However, the lines can easily become blurred.
For example, a SEAL team was parachuted into the Pacific to rescue a solo civilian sailor who had medical problems beyond the ability for a medevac. They boarded his sailboat and sailed it within range of an air/sea rescue medevac. SEALs are usually thought of as combat divers, but in this case the mission was 100% purely peacetime rescue.
Air Force Para Rescue, while thought of us rescuing downed pilots can become as combative as SEALs under fire.
A kid making a few bucks doing hull-scrubbing with a Brownie's Third Lung or harvesting red kelp in Alaska for a week, is certainly doing commercial diving work, but isn't really a commercial diver as we often think of them.
A tourist paying for a liveaboard vacation to help Dr. Eugenie Clark with shark research is not really a scientific diver, yet is doing precisely what science assistants do to help researchers at the most elementary level.
While I'm a lifeguard (and have used scuba to do that job) and member of the International Underwater Cave Rescue and Recovery teams, I really don't consider myself to be a true public-safety diver.
Individuals choose to like or dislike certain terms. Frank Murphy of PDIC used to hate the term "tank" and insisted on the term "cylinder" instead. I don't mind either and I use both. Terminology does help us to sort and file. The fact that you can read and understand this post and paint pictures in your mind of technical, recreational, scientific, commercial and military divers proves the effectiveness of terminology whether you like it or not or whether that terminology clearly defines a diver or not. The terminology does help us to create a stereotype or best example of something and benchmarks how far from the best examples of various diving endeavors an activity, or type of diver, may be categorized.