[[File:Hjälmaren in Sweden.png|thumb|left|Lake Hjälmaren (see red arrow)|180px]]
'''Hjälmaren''' ({{IPA-sv|ˇjɛlːmarɛnˈjɛ̂lːmarɛn}} <small>or</small> {{IPA-sv|ˇjɛlːmaɳˈjɛ̂lːmaɳ|}}<ref name="Bergman">{{cite-book|url=http://runeberg.org/ortnamn/0016.html|author1=Jöran Sahlgren|author2=Gösta Bergman|title=Svenska ortnamn med uttalsuppgifter|language=sv|year=1979|page=12}}</ref>), also spelled '''Jälmaren''',<ref name="Bergman"/> is [[Sweden]]'s fourth largest lake. It is situated in the [[Central Swedish lowland]] and drains through [[Eskilstunaån]] into the adjacent Lake [[Mälaren]], which in turn drains into the [[Baltic Sea]], west of [[Stockholm]]. It is connected by waterway with Stockholm by the 13 kilometres long [[Hjälmare kanal]].
It is bounded by the [[Provinces of Sweden|provinces]] of [[Södermanland]], [[Närke]], and [[Västmanland]].