Pettson and Findus are having fun skimming stones across the lake, until Pettson takes a tumble and falls into the water. He splashes around till he finds his footing, but Findus is not very impressed with his swimming skills. Pettson tells him he is a very good swimmer and was given a ‘guppy badge’ when he was young, by the famous swimmer Arne Borg, so this proves he can swim.