Scuba diving is an "Adjustable Risk" sport that can be an extreme sport.
Actually skydiving is also an adjustable risk sport to some degree as you can do a hop and pop at 4000 ft and come down under a large and easy to fly canopy. Alternatively you can jump at 15,000- 20,000 ft, do relative work at very high speeds in freefall on the way donw and/or do canopy relative work with other skydivers and/or mow the lawn while landing under a very small and fast canopy, all of which are a bit more dangerous and can result in minor to fatal injury if you screw up. Or you can just go crazy and do base jumping off tall objects with no reserve chute (no time to use one if you had it anyway.) which is not only dangerous but usually illegal (illegal trespass, breaking and entering, creating a public nuisance, disorderly conduct, etc) which ups the adrenaline factor a bit more for the serious addicts.
In comparision, diving is pretty tame but the potential still exists to dial up the difficulty/danger level to a point that gives you that edge of fear. Personally, I like deeper technical diving as it allows you to push things just far enough to force you to focus and to feel that little edge of fear that keeps you sharp. I would not go so far as to call it "dangerous" when properly done, as but then I also do not regard run of the mill skydiving as particularly dangerous either when properly done.
Given that I think for a living and am usually juggling several issues at any one time during the work week, I find a fairly demanding level of diving that prompts that cautionary/warning level of fear to be very relaxing as it forces me to focus only on diving. Consequently during the planning and execution of that dive, I am not thinking about anything else, which is ultimately very restful to me.
Diving used to be recognized as more of an extreme sport before the term was coined, but about 25 years ago diving became big business and it became very important to the industry to change the image so that it would appeal to more women, middle age couples, etc in order to greatly expand the potential market. (I won't even go into the watering down of course content, standards, etc that has occurred to accommodate this new market.) So now, even when diving is very extreme, the industry as a whole is going to claim it is not in order tp maintain the widely marketable safe family sport image.
But PC marketing BS aside, you can still make diving as risky as you want it to be.