The Wiese Valley Railway (German: Wiesentalbahn) is a 27.2 km long, electrified main line in German Baden-Württemberg in the tri-national area of Germany, Switzerland and France near the Swiss city of Basel. It is part of the Basel trinational S-Bahn and referenced as S6. It runs alongside the river Wiese from Basel Badischer Bahnhof in Basel (on Swiss territory) to Zell (Wiesental). It is operated by the Swiss Federal Railways (SBB CFF FFS)