Tinnsjå

From Wikipedia, the free encyclopedia

Tinnsjå
Location	Telemark
Coordinates	59°54′N 8°55′ECoordinates: 59°54′N 8°55′E
Primary sources	Måna
Primary outflows	Tinnelva
Basin countries	Norway
Surface area	51.43 km²
Max depth	460 m
Water volume	9.71 km³

Tinnsjå (Tinnsjø, Tinnsjøen) is a major Norwegian lake -- the 3rd deepest, 6th largest by volume and 20th largest in surface area in the country. It is located between the municipalities of Tinn and Notodden in Telemark county. On its source: From the west, the Måna river flows out of Møsvatn and past Rjukan into Tinnsjå. From the north, the river Mår flows from Mår, Gøystavatn and Kalhovdfjorden lakes and joins the Måna river before entering Tinnsjå. Tinnsjå is part of the Skiensvassdrag, and drains via the Tinnelva river in the south, down to Heddalsvatn.

In 1944, during the German occupation of Norway, the ferry D/F Hydro was sunk in Tinnsjå by the Norwegian resistance. The Germans were using the ferry to transport a large quantity of heavy water to Germany, where it was to be used for nuclear weapon research. The heavy water had been produced at Vemork, a factory located in Rjukan.

The wreck of the ferry was discovered in 1993. In 2004, it was investigated and filmed for an episode of the American public television; heavy water samples were recovered and deuterium isotopic enrichment was confirmed.

In April 2005, a previously unknown species of fish was discovered in Tinnsjå. A film crew shooting footage for a new documentary on the heavy water sabotage became aware of an unusual fish, swimming near the lake bottom at a depth of 430 m. The light-colored, translucent fish was about 15 cm long and seemed to lack a swimming bladder.