Southend is a town and locality in the Australian state of South Australia located in the south-east of the state on the southern shore of Rivoli Bay about 324 kilometres (201 mi) south-east of the state capital of Adelaide.

Rivoli Bay is a bay located on the south-east coast of the Australian state of South Australia, about 311 kilometres south-southeast of the state capital of Adelaide and about 65 kilometres northwest by west of the regional centre of Mount Gambier. It was named in 1802 by the Baudin expedition of 1800–03 after André Masséna, the Duke of Rivoli and Marshal of France. It is one of four 'historic bays' located on the South Australian coast.