It looks like you're looking for the 1980 Swedish children's film (English title: Children's Island ), possibly to watch on ok.ru.
The story follows 11-year-old (played by Tomas Fryk ), an introverted boy living in a Stockholm suburb. When his mother expects him to spend the summer at a traditional camp called "Children's Island," Reine secretly stays behind in the city instead. barnens ö (1980) ok.ru
A quick note: Ok.ru (Odnoklassniki) is a social network that hosts user-uploaded videos, including many older films. While links there can change or be taken down due to copyright, I can guide you on how to search for it effectively. It looks like you're looking for the 1980
Barnens ö (Children's Island) – 1980