Uncle Blue's New Boat by Elsa Beskow
This is the adventure of Peter and Lotta and their trip in Uncle Blue's new boat. The children set out for a picnic on an island together with the three colourful aunts, Aunt Green, Aunt Brown and Aunt Lavender. While the adults are having a nap, Peter and Lotta decide to go and practise their rowing, but disaster strikes when they become distracted and accidentally lose the oars