The boss and myself paddle around a lake in SA one board with the 5 year old on board and the second board with the 2 year old. We paddle for a bit and stop at a playground, they play, we then jump back on and paddle to the next playground etc etc for the 6 km around the lake. Last time the 2 yo feel asleep for the last 2 km, with water lapping across his face in the 15 knot headwind.
Will do it again this summer but might be a bit harder on the Ace