Divide den into 2 equal teams.  Supple each Cub Scout with a piece of rope about 2 feet long.  One cub from each team sits on a piece of cardboard some distance from the rest of his team.  Each Cub must tie rope to his neighbors using a square knot.   When all ropes are tied, one end is thrown to the Cub on the cardboard and his team pulls him to safety (pass a line on the ground).  First team to pull in Cub is the winner.