Wikipedia
Sommen is a Swedish lake. Its area is 132 km² and its greatest depth is 60 m.(although deeper places are found every year) The lake is located in southern Sweden, and is bounded by the provinces of Östergötland and Småland.
The lake is a clear-water lake, with a visibility of 9–11 m in the eastern parts of the lake. This makes Sommen one of the greatest clear-water lakes in Sweden.
According to tradition Sommen has 365 islands, one for each day of the year. The actual number is around 350.
Legend has it that the lake was created by an ancient cow "Sommakoa". The wizard who owned her tried to chain her to a fence to calm her fits of anger. Sommakoa broke lose from her chain, stomped her hoof very hard into the ground and then ran off. The foot print filled with water creating the lake.
There is an annual bicycle race around the lake every May called Sommen Runt (around Sommen)
There is a very active boating culture on Lake Sommen. With several regattas organized each year the longest is called Sommen Runt (Around Sommen) and takes two days and one night to complete as the route follows the unusual shape of the lake.
Sommen is also the home lake of one of Sweden's last woodfueled steamboats; the S/S Boxholm II.