for the river kayaks, the shorter ones are more maneuverable and the longer ones are faster and can generally carry more. Kayaks tend to need deeper water than a pontoon. Kayaking in a shallow river, the kayak will hang up on a rock then the water will tend to turn you perpendicular and flip you over. You have to climb out, generally undo the skirt attachment slows you a little too. And then getting back in you need to find a launch point again, hook the skirt up, etc. For a pontoon, you can hop off and slide it over a shallow area and hop back on, back on your way. But if you use on a lake, a pontoon kind of sucks. Wind blows you around and they don't row as nicely or fast as a kayak.
