A whole day filled with only play and pranks! Pelle wants such a day, and Melker is not particularly difficult to persuade. Off it goes to Dead Bay where the old galeas Albertina lies. Here two terrible pirate gangs will fight for Mysak - the world's largest diamond! Albertina becomes the headquarters of the Sharks, led by the dreaded pirate Tiger Shark - awfully similar to Tjorven if you look closely. The enemy Hawks are led by the Hawk, who actually looks a bit like Uncle Melker. Bathing with his clothes on, so does the Hawk, just like Uncle Melker usually does…The script for Tjorven and Mysak was written directly for the film by Astrid Lindgren. The film was the third in the series about the children at Saltkråkan and their summer adventures. Most of the film was shot on Åland in connection with the old schooner in a bay. The "magic object" Mysak was a small miniature sculpture in enamel, made by the artist Karl Axel Pehrson.The four Saltkråkan films were also divided into a TV series in 12 episodes in 1977: That's how it's done at the Saltkråkan.