Years ago I built a PedalCraft that would have been a lot of fun on smaller lakes but I was in a hurry, short on funds, and unfortunately the pontoons were not sealed correctly and took on water.  It was pedal powered like a bicycle, steerable by a simple Joystick by the seat, which was comfortable to sit in, had a spot for an Ice Cooler right behind the seat, and was simple to assemble on the shore in just a couple minutes.  It was slower than I wanted, which could have been fixed easy enough.  It all came down to the pontoons which would probably have been fine with a little bit of fiber glassing that I didn't know how to do, and a more durable propulsion system.  If I ever get the chance, I would like to build another, more advanced model.