[1]) is a 19.2 km (11.9 mi) long line in the German state of Baden-Württemberg.

The line is electrified to the standard 15 kV, 16⅔ Hz system commonly used throughout the German railway network.

[2] The Dreiseenbahn branches southwards from the Höllentalbahn railway, from Freiburg im Breisgau to Donaueschingen, at Titisee station.

Along its route it serves stations and halts at Feldberg-Bärental, Altglashütten-Falkau, Aha and Schluchsee, before terminating at Seebrugg.

[2] The line is so called because it passes by the three lakes of Titisee, Windgfällweiher and Schluchsee.