Hjalmaren

Lake Hjälmaren became more closely connected with Sweden's inland trade when the Hjälmare Canal opened in 1639. The waterway linked the lake with the Arboga River and Lake Mälaren, providing a route toward Stockholm. One of its principal purposes was to carry iron from the Bergslagen mining districts to the capital and onward to overseas markets.

The canal demanded repeated rebuilding. A major repair campaign in 1691–1699 involved Nicodemus Tessin the Younger and canal specialists from the Netherlands. Between 1819 and 1829 a new five-kilometre alignment was constructed on the initiative of Baltzar von Platen. These works altered the routes by which boats reached the lake and show how Hjälmaren's commercial connections depended on maintained locks and channels as well as on its natural waters.