Diving within rec limits strikes me as considerably less dangerous than many or maybe most other rec activities. One clear difference in favor of diving is that there's not much danger from the actions or inactions of others when I dive. More directly, there are only a couple of fatality or serious injury risks uniquely related to open circuit SCUBA underwater, which are pretty easy to minimize while still diving fun, fascinating, and diverse locales. You can certainly make it more dangerous by choice of conditions, equipment, and profiles - and some of judgement in those regards probably only comes about through experience, meaning surviving danger. Yet I don't find that my pursuit of experience or fun draw me all that much in the direction of those dangers, so for myself at least I think it's fair to say diving isn't so dangerous, relative to other outdoor activities.
I've never jumped out of a plane in a squirrel suit - though it looks amazingly, terrifyingly, FUN - but I don't consider it proof that jumping for the fun of free-fall is dangerous.