Visingsö

Visingsö
Island
Country	Sweden
County	Jönköping
Location	Vättern
- coordinates	58°03′N 14°20′E / 58.050°N 14.333°E / 58.050; 14.333Coordinates: 58°03′N 14°20′E / 58.050°N 14.333°E / 58.050; 14.333
Area	25.04 km2 (10 sq mi)
Visingsö in lake Vättern

Visingsö is an island in the southern half of Lake Vättern in Sweden.

Visingsö lies 30 kilometres (19 miles) north of the city Jönköping and 6 kilometres (3.7 miles) west of Gränna from which two car ferries connect the island. The island is 14 kilometres (8.7 miles) long and 3 kilometres (1.9 miles) wide, with a total area of 24 square kilometres (9.3 square miles).

According to legend, a giant named Vist created Visingsö by throwing a lump of soil into the lake so that his wife could use it to step over the lake.

In the 12th and 13th century, Näs Castle on the southern end of Visingsö was the residence for the fragile Swedish monarchy. Four Swedish kings died there: Karl Sverkersson, Erik Knutsson, Johan Sverkersson, and Magnus Ladulås. Furthermore, in the 17th century the influential Brahe family resided in Visingsborg, a castle on the eastern side of the island. Both Näs Castle and Visingsborg are presently ruins and well known landmarks of Visingsö.

The Swedish Navy planted oak trees on the island in the 19th century to provide strategically important timber for future ship construction. The timber is now ready but no longer required for ship construction. Consequently, Visingsö is partially covered by oak forests, the rest being farmland.

Visingsö has long been of interest to geologists because of the development of a sedimentary series of rocks (the Visingsö Group) there (and elsewhere around Lake Vättern, especially on the west side). The surrounding rocks are largely much older "Småland granites" of mixed granite-like compositions. The Visingsö Group is approximately 1000 m thick and is divided into three units. It is Late Riphean in date. A wide array of late Precambrian fossils have been recovered from the group, including stromatolites, vase-shaped microfossils, acritarchs and macro fossils such as Chuaria. The sediments of the Visingsö Group have been preserved within the Lake Vättern graben structure.