Lake Vättern

Lake Vättern is at most 31 km wide and 135 km long, measured from Jönköping in the south, to the town of Askersund at its northern end. In all, the lake covers an area of some 1,900 km². Having an average depth of 40 metres, the largest known depth is 128 metres south of the island of Visingsö. The lake´s water turnover rate is, on average, some 60 years.

Geologically, Lake Vättern is a fault trough, i.e. a deep valley with steep walls, which has sunk in relation to its surrounding land areas. Following the Ice Age, some 10,000 years ago, it became a lake from previously being a bay of the sea, trapping the existing natural salt water fauna. Some of the original species, for example char and grayling, have adapted to their new habitat and are still fished and caught in the lake.

Visingsö is the largest island in Lake Vättern and is part of the Municipality of Jönköping. It is 14 km long and some 3 km at its widest. It has many interesting ancient monuments and remains which document all the ages of human settlement. The island is a much appreciated tourist destination, offering a rich variation of cultural treasures and historical sites and is easily reached using the frequent ferry services from Gränna town.