Rjukan Falls (Norwegian: Rjukanfossen) is a waterfall of 104 metres in the western part of the Westfjord valley in Tinn, a municipality in the county of Telemark, Norway, west of the industrial town Rjukan. The waterfall is a part of the Måne river, earlier a major tourist attraction, being one of the first floodlighted waterfalls by electricity produced by the same waterfall. In 1905 Rjukan Falls was built out to produce hydro electrical power for the saltpetre production when Norsk Hydro was established.
The name (West Norse Rjúkandi) is derived from the verb rjúka 'to smoke' (referring to all the froth from the waterfall). The last element fossen, the finite form of foss 'waterfall', is a later addition.
Coordinates: 59°52′1″N 8°28′45″E / 59.86694°N 8.47917°E / 59.86694; 8.47917
Rjukan is a town and the administrative centre of Tinn municipality in Telemark, Norway. It is situated in Vestfjorddalen, between Møsvatn and Lake Tinn, and got its name after Rjukan Falls ('the smoking waterfall') west of the town. The Tinn municipality council granted township status for Rjukan in 1996. The town has 3,386 inhabitants (Jan. 2007).
Rjukan was formerly a significant industrial centre in Telemark, and the town was established between 1905 and 1916, when Norsk Hydro started saltpetre (fertilizer) production there. Rjukan was chosen because Rjukan Falls, a 104-metre waterfall, provided easy means of generating large quantities of electricity. The man with the idea to use the Rjukan falls was Sam Eyde, the founder of Hydro. It is estimated that he, together with A/S Rjukanfoss (later Norsk Hydro), used about two times the national budget of Norway to build Rjukan and that there were approximately 12,000 workers (Rallare) from Sweden, Denmark, and Finland, as well as Norway building the factories and the town.