Lock is a town in the centre of Eyre Peninsula in South Australia. It is central Eyre Peninsula's main grain storage hub, as it is surrounded …Lock is a town in the centre of Eyre Peninsula in South Australia. It is central Eyre Peninsula's main grain storage hub, as it is surrounded by a predominantly farming community, with emphasis on cereal crop production. The town has a hotel, caravan park, motel, supermarket, post office, police station, library, sporting complex, golf and bowling clubs and area school. At the 2006 census, Lock had a population of 290.