Ideally, I want to find a steep and narrow canyon - with waterfalls to abseil, rock smooth enough to slide, and pools deep enough to jump in.
But, I would genuinely be happy with anything here -
Swimming spots, Jump pools, or gorges to scramble through.
Big, short, long and small rivers are all of interest right now.
I already guessed that it would be prohibited in the national parks, but that isn't too uncommon even outside of Korea. Canyoning is often something that has to be done discreetly - although I'm not too keen on getting in trouble.
Since posting this I actually found a couple of trip reports posted online. They're not exactly what I was looking for - but they are promising.
I have a growing list of places to check out - but most of these are just touristy spots. The availability of useful English language information has been fairly limited.
Looking at the terrain here - I think there ought to be some good descents to explore. It's just a matter of finding the information - and sharing it.
I've just started a facebook page (Korean Canyoning) - but I haven't pushed it yet, because I still don't really have anything to share.
Really, just the fact that a few people have expressed some interest is promising enough.