Normal spelunking, minimal vertical work, the occasional belly crawl no smaller than a manhole. That’s actually a pretty good time. You get wet, dirty, have a few laughs with your friends, and then shake it off with some beers back at the campsite. No need to go aggressive with ridiculously tight crawls and/or 100’s of feet of vertical work, etc.
Cave diving? Let’s take an activity where it’s very easy to loose track of time, and add SCUBA which requires time management down to the minute for your health and survival. Nevermind getting lost, disoriented, or wedged underwater somewhere. I get that this is very intrepid stuff, and the very distant corners of cave systems are being explored this way. But it’s a big no for me; the risk does not justify the reward, IMO.