The Spencer Gulf is the westernmost and larger of two large inlets (the other being Gulf St Vincent) on the southern coast of Australia, in the state of South Australia, facing the Great Australian Bight. It spans from the Cape Catastrophe and Eyre Peninsula in the west to Cape Spencer and Yorke Peninsula in the east.
The largest towns on the gulf are Port Lincoln, Whyalla, Port Pirie, and Port Augusta. Smaller towns on the gulf include Tumby Bay, Port Neill, Arno Bay, Cowell, Port Germein, Port Broughton, Wallaroo, Port Hughes, Port Victoria, Port Rickaby, Point Turton, and Corny Point.