Thun (German: [çu̯oːn]; French: Thoune) is a city and municipality in the administrative district of Thun in the canton of Bern in Switzerland with about 43,783 inhabitants (around 90,000 in the agglomeration), as of 31 December 2013.It is located where the River Aare flows out of Lake Thun (Thunersee), 30 km south of Bern.