Långhalsen is a lake predominantly in

Nyköping Municipality Nyköping Municipality ( sv, Nyköpings kommun) is a municipality in Södermanland County in southeast Sweden. Its seat is located in the city of Nyköping, which is containing a majority of the residents. Its southern tip in the district of Tuna ...

, Södermanland,

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 ...

that is part of the

Nyköpingsån Nyköpingsån is a river primarily flowing through Södermanland County in Sweden. The river is named after Nyköping, where it flows into the Baltic Sea. Nyköping is also the largest settlement on the river proper and a large part of the drainage ...

drainage area. There is a very small portion of the lake's northern inlet that is part of Flen Municipality. There are three nearby lakes directly connected to its north that also are named Långhalsen due to their similar shapes, although they are considered separate lakes due to being connected by narrow rivers and straits. The lake surface is located at above sea level with multiple inlets and has several islands, the highest of which rises to .

References

Lakes of Södermanland County {{Södermanland-geo-stub