Lake Mälaren

Lake Mälaren is the third-largest lake in Sweden, after the lakes vänern och vättern. Its area is 1,140 km² and its greatest depth is 64 m. The lake drains into the Baltic Sea through Södertälje kanal, Hammarbyslussen, Karl Johanslussen and Norrström. The lake is located in Svealand. The two largest islands in Mälaren are Selaön an Svartsjölandet.
There is a Viking age settlement called Birka on the island of Björkö and Hovgården.

Utter Inn, or Otter Inn as its called in English, is an art project by Mikael Genberg which offers underwater accommodation to the public. The facility is entered through a typical Swedish red house located on the surface of the water. The only representation of this concept is, at this point, located in Lake Mälaren near the town of Västerås in Sweden. It is a hotel for two persons.