Lake Trasimeno (Italian: Lago Trasimeno, Italian pronunciation: [ˌlaːɡo traziˈmɛːno]; Latin: Trasumennus; Etruscan Tarśmina), also referred to as Trasimene or Thrasimene in English, is a lake in the province of Perugia, in the Umbria region of Italy.
The lake is south of the river Po and north of the nearby river Tiber, has a surface area of 128 km2 (49.4 sq mi) and is the fourth for surface area in Italy. (It is slightly smaller than Lake Como.)
Only two minor streams flow directly into the Lake and none flows out. The water level of the lake fluctuates significantly according to rainfall levels and the seasonal demands from the towns, villages and farms near the shore.