My father too built a canoe of wood and canvas. He might have sent away for plans.
I tried white-water canoeing and kayaking, but I never will do that again -- too dangerous. The kayaker in this photo has a serious life vest and helmet. The water looks deep enough that the kayaker probably won't get any body parts wedged underwater between rocks. In places downstream, there are whirlpools; for example, see https://pbase.com/ralph_s/image/156195636
As a young man I built a canoe out of scrap wood and canvas.
I enjoyed canoeing very much. Even if we had rivers like this I would not have gone on them. I like being on water as flat as possible.