Visingsö

Furthermore, in the 17th century the influential Brahe family resided in Visingsborg, a castle on the eastern side of the island.

The Swedish Navy planted oak trees on the island beginning in 1831 to provide strategically important timber for future ship construction.

[2][3] Visingsö has an oceanic climate (Köppen Cfb), influenced by its position in the middle of the deep lake.

As a result of Vättern's depth, it struggles both freezing over in winter as the surrounding landmass is colder, while in summer the temperature of the lake remains fairly cool.

In spite of the unfavourable conditions for heat in its deep-lake position, Visingsö has warmer summers than all of the island of Ireland as well as much of Great Britain.