Has AG heard of bike polo? It is like polo where you ride on horses and whack a ball with a crochet mallet but you are on bikes and you don't use crochet mallets. But it seems a bit dangerous and hard. Dangerous because you are slamming into each other on bikes going 25mph. Hard because of the fact that you are going so fast and in such a small area. For more info I have provided a link.
Ummmmm.... Staying afloat on two buoyant wheels would be extremely hard and potentially lethal. You could get hit by a boat, run into a wave, just fall over, get attacked by a shark and die.
I had to relook at what the subject actually was. Ya i dont know anything about bike polo but it sounds kida cool, if you can imagine a bunch of grown men on floating tricycles throwing around a ball. Haha XD