I have a Parkour Map that is the hardest ever. It is all possible, but nobody can do the whole thing, and I don't think they can. This map is extremely hard and very long. You should only attempt this if you are the best of the best. It encompasses huge jumps, parkour, freerunning, and river rapids. If you think you are that good you can download the map here: http://www.planetminecraft.com/project/hardest-parkour-experts-only/
but be warned; this is for experts only! If you do complete it or do it mostly and want to prove it make a video and I will post it on the map's page.

Good luck!