Dismal Swamp is a locality in the Australian state of South Australia located about 361 kilometres (224 mi) south-east of the state capital of Adelaide and about 19 kilometres (12 mi) north-west of the municipal seat of Mount Gambier.

[1][4] Boundaries for the locality were created in February 1999 for the “long established name.”[1][3] The name Dismal Swamp was used as early as 1845 when Anthony Sutton used the name for an occupation license on land described as being near Tarpeena.

It is possible the name was inspired by the Great Dismal Swamp in the United States of America.

[9] Dismal Swamp is bounded on its east side by the Riddoch Highway which passes through the locality from north to south[1] The Mount Gambier railway line which has been closed to freight since 12 April 1995 and tourist services since 1 July 2006,[citation needed] passes from north to south through the locality.

[1][12][13] Dismal Swamp is located within the federal division of Barker, the state electoral district of Mount Gambier and the local government area of the District Council of Grant.