The Lötschberg Tunnel is a 14.612 km (9.079 mi) long railway tunnel on the Lötschberg Line, which connects Spiez and Brig at the northern end of the Simplon Tunnel cutting through the Bernese Alps of Switzerland. Its ends are at the towns of Kandersteg in the canton of Bern and Goppenstein in the canton of Valais. The top elevation of the tunnel is 1,240 m (4,070 ft) above sea level, this is the highest point of the main Swiss railway network.

The Lötschberg line is a railway in Switzerland, connecting Spiez in the canton of Bern with Brig in the canton of Valais. It crosses the Bernese Alps, from the Bernese Oberland to Upper Valais, through the Lötschberg Tunnel in the middle of the line. Together with the Simplon Tunnel south of Brig, it constitutes one of the major railways through the Alps and an important north-south axis in Europe. The Lötschberg axis is backed by the lower and longer Lötschberg Base Tunnel, part of the New Railway Links through the Alps project.