Tyin is a lake in the southwest part of the Jotunheimen mountain range in Norway. The lake lies in Vang municipality in Oppland county, although a small portion extends into Årdal municipality in Sogn og Fjordane county. The western border follows, for a large part, the border between Vang and Årdal. In area it is 33.02 km². The lake serves as a reservoir for Tyin kraftverk and the water level is regulated between 1082.84 and 1072.50 m above sea level.