Zimmerberg mountain is located some 15 km (9.3 mi) in the southeast of the city of Zürich, between Langnau am Albis in the Sihl Valley (German: Sihltal) and Rüschlikon and Horgen on the Lake Zurich, overlooking Sihl valley, the Albis hills, Lake Zurich and Pfannenstiel. Points of interest include Hüttnersee and, on the neighbouring Albis chain, Albishorn (909 metres (2,982 ft)), Bürglen mountain (914.6 metres (3,001 ft)), the observation tower near Schnabelburg, the Albis Pass, Felsenegg and the extensive woods known as Sihlwald. Sihl river borders Zimmerberg on its southern side, on the northeastern side it is bordered by the Lake Zürich. The area is wooded, but also has extensive fields, some cultivated. Being near the city Zurich, the area is a known recreation area.
The area alongside Lake Zürich had been formed as the left moraine of the Ice Age glacier, the bed of which is now the Lake Zürich and the valley of the Sihl river. The soil is mostly a conglomerate of gravel, some of it large, and glacial loess.
Zimmerberg Base Tunnel is a railway tunnel divided into two parts: The first is about 10 km (6.2 mi) long and links Zürich and Thalwil; the second part will bring the length to about 20 km (12 mi) linking Zürich and Zug.
