Belomorsk is a town and the administrative center of Belomorsky District in the Republic of Karelia, Russia, located on the Onega Bay on the sh…Belomorsk is a town and the administrative center of Belomorsky District in the Republic of Karelia, Russia, located on the Onega Bay on the shore of the White Sea. Population: 11,217 ; 13,103 ; 18,935.