The Furka Base Tunnel is a Swiss railway base tunnel on the Matterhorn Gotthard Bahn's Furka–Oberalp line, an east–west railway connecting the cantons of Valais and Uri. Its west portal lies east of Oberwald (VS), at 1,390 m (4,560 ft) above sea level and its east portal lies south of Realp (UR), at 1,550 m (5,090 ft).

Prior to its construction, all traffic had to use the historic high-level route via the 1.8 km (1.1 mi) long Furka Summit Tunnel, which was only available seasonally due to the threat posed by heavy snowfalls. Construction commenced during 1971, taking ten years to complete. An innovative permanent support system was used, comprising rock anchors and a shotcrete coating, which included the first use of polyurethane-based grouting within a railway tunnel. The tunnel has a relatively narrow cross section, which has been attributed with slowing the construction effort somewhat.