You might want to check out inflateable boating. My brother likes it for lake and river "floating" and claims that the fabric is rugged and durable.
As you probably know, the US Army Rangers use these inflatable boats. I saw these boats at an army surplus auction one time, but the government had de-miled them, by mutilation, making them unseaworthy. The material was very, very thick.
You might want to check out Sea Eagle, although my brother bought his inflateable from Gander Mountain, I think.