It runs from Gossau via Appenzell to Wasserauen in Switzerland and is given the abbreviation of GAW by the operator.

The connection was built and electrified in several stages by different companies and has been operating continuously since 1949.

The line was developed in the following stages: In order to be able to carry standard-gauge wagons on the metre-gauge network, a Rollbock system was opened in Gossau on 1 July 1978, allowing operations on the Gossau–Wasserauen route.

As of the December 2021 timetable change,[update] Appenzell Railways operates half-hourly service between Gossau SG and Wasserauen.

[4] In addition to regular station stops, the S23 stops on request at Gonten Alpsteinblick, between Jakobsbad and Gontenbad, to serve the Alpsteinblick ski lift.