Södermanland borders the counties of Östergötland, Örebro, Västmanland, Uppsala, Stockholm and to the Baltic Sea.

It holds the popular camping route called "Sörmlandsleden" which is a system of trails covering a total of approximately 100 mil (1000 km) of walking paths in Södermanland.

The eastern parts of the Södermanland province, largely corresponding to the Södertörn area, belong to Stockholm County.

The centre of Södermanland is spread out between four municipality seats namely Vingåker, Katrineholm, Flen and Gnesta that separate the southern and northern areas of the county.

The interior of Södermanland has many small rolling hills, courtesy of glacial rebound that has shaped the landscape of the area.

Summers highs are most often around 23 °C (73 °F), with lows around 12 °C (54 °F) inland and either near or above 14 °C (57 °F) on the coast due to the warm July sea surface temperatures.

[4] As of 2019, the local government constellation consists of the Social Democrats, Vård för Pengarna[5] and the Centre Party.

[6] The table details all Riksdag election results of Södermanland County since the unicameral era began in 1970.