What is the ship that sank in the Baltic sea and is in the novel Salt to the Sea?
Salt to the Sea:  It tells the story of four individuals in World War II who make their way to the ill-fated MV "Wilhelm Gustloff". MV Wilhelm Gustloff: MV "Wilhelm Gustloff" was a German military transport ship which was sunk on 30 January 1945 by  in the Baltic Sea while evacuating German civilians, Nazi officials and military personnel from Gdynia (Gotenhafen) as the Red Army advanced.
MV "Wilhelm Gustloff