They were named after the Frisian Islands : Lager Norderney , Lager Borkum , Lager Sylt and Lager Helgoland . They were named after the Frisian Islands ( this was probably the Germans trying to show what would happen to Britain , as it were ) : Lager Norderney , Lager Borkum , Lager Sylt and Lager Helgoland .