Sillen is a lake in
Södermanland
Södermanland ( or ), locally Sörmland, sometimes referred to under its Latin form ''Sudermannia'' or ''Sudermania'', is a historical province or ''landskap'' on the south eastern coast of Sweden. It borders Östergötland, Närke, Västmanla ...
,
Sweden
Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...
. It straddles the boundary between
Gnesta Municipality
Gnesta Municipality (''Gnesta kommun'') is a municipality in Södermanland County in southeast Sweden. Its seat is located in the town of Gnesta, with some 5,000 inhabitants.
The present municipality was created in 1992, when Nyköping Municipal ...
in
Södermanland County and
Södertälje Municipality
Södertälje Municipality (''Södertälje kommun'') is a municipality in Stockholm County in east central Sweden. Its seat is located in the city of Södertälje.
It borders to Lake Mälaren in the north and the Baltic Sea in the south, and withi ...
in
Stockholm County
Stockholm County ( sv, Stockholms län, link=no ) is a county or '' län'' (in Swedish) on the Baltic Sea coast of Sweden. It borders Uppsala County and Södermanland County. It also borders Mälaren and the Baltic Sea. The city of Stockholm ...
.
Lakes of Södermanland County
Lakes of Stockholm County
{{Stockholm-geo-stub