Tumby Bay is a coastal town situated on the Spencer Gulf, on the eastern coast of Eyre Peninsula in South Australia, 45 kilometres (28 mi) north of Port Lincoln. The town of Tumby Bay is the major population centre of the District Council of Tumby Bay, and the centre of an agricultural district farming cereal crops and sheep, as well as having established fishing and tourism industries.

Tumby Bay is normally reached by private car via the Lincoln Highway that runs along the east coastline of the Eyre Peninsula. Although the town does have a sealed airfield, it is not usually used for private flights, but for the Royal Flying Doctor Service and crop spraying aircraft.