South Channel or Broad Sound South Entrance Channel is one of three shipping channels in the United States connecting Boston Harbor to Massachusetts Bay near Boston, Massachusetts. [1] [2] Starting at the eastern end of the President’s Roads anchorage, the channel passes north of Lovell's Island and Ram’s Head Flats, then northwest of Aldridge Ledge and the Devils Back. [3] It is dredged to a 30-foot depth. [2]