Kayaking at least (not sure how much concentration pottery needs) would give you a _lot_ of time to just stare at the beauty of nature and think. Now this may or may not result in anything, but if you are reasonably intelligent and trying to improve yourself but you are lacking the 'downtime' to just let your mind wander then kayaking might do the trick for you. Best combined with a good book for when you're in camp, so that you can read some other bright people's ideas and incorporate them into your thinking process, the pros and cons of what they're saying for your own life etc.
I dearly love both sports and reading, but they are very different activities that give you happiness in very different ways. Kayaking won't teach you quantum mechanics or ancient Greek history. So from a certain knowledge-adquisition point of view, pottery and kayaking are way less efficient, if not a waste of time. Just like reading is a waste of time from the physical happiness POV.
As with most things in life, a good balance is needed.
