Northern Spencer Gulf is a broad, shallow marine embayment forming the landward extremity of Spencer Gulf, sheltered between the Flinders Ranges and the Eyre Peninsula in South Australia. This region, often referred to as Upper Spencer Gulf, extends from Port Pirie north to Whyalla and Port Augusta. It is characterized by fertile, sheltered waters that serve as a vital nursery area for a wide range of fish and crustaceans, supporting a rich and diverse marine ecosystem. The area is internationally recognized for its significant breeding population of the Giant Australian Cuttlefish and includes wetlands of national importance.