So we've tried Caynoning this weekend. Basically the sport consists of wearing a neoprene suit and then following a canyon from the top to the bottom by jumping or rappelling, walking and swimming. I was a little bit afraid beforehand on what we were to expect, but it proved to be rather easy. The tour was also one for beginners (not total beginners, but easy enough).
The first cool thing that I experienced was the neoprene suit. It has some very nice and fascinating properties. First is that it's quite warm despite a water temperature of just 6°C (~43°F) and second: It exhibts a buoyant force (Auftrieb) which is very nice as it makes swimming an easy task and prevents you from sinking. This makes jumping especially fun, as the suit will bring you back to the surface in no time (and you don't even experience much of the wetness or the cold water). There were two higher jumps during the tour, one with 6.5 metres and the other with 9 metres being quite a jump already, as well as a few smaller jumps.
Overall the tour was quite fun, although a little tedious as well. The canyon was very beautiful sometimes, but there wasn't so much time to enjoy the beauty as we were in the middle of three groups and our guide stopped just a few times. At the end we were a little "lustlosly" stomping through to the end.
I didn't experience this so much during the tour, but it was quite exhaustive and so I was extremly tired falling into bed at home.
Followup: One week later and there were two accidents with two injuries reported in local news. One of them seems to be in the same canyon even.