Viamala, Slot canyon and tourist site in Grisons, Switzerland.

Viamala is a gorge along the Hinterrhein between Thusis and Zillis-Reischen, cut into dark grey rock on the left and lighter layered stone on the right, with a turquoise channel at the bottom. A stone arch bridge spans the cliff tops above. A staircase of 321 steps, starting at a car park with a kiosk, leads down to the narrowest point and a whirlpool.

A path through the gorge existed in Roman times, cut into the left wall as rock galleries. In 1473 Thusis, Masein and Cazis rebuilt the passage and erected Punt da Tgiern, the first stone bridge. The 1834 flood destroyed its access, and the Rania bridge replaced it in 1836.

The name Viamala comes from Romansh "veia mala", meaning "bad path", used for the gorge and route since the 13th century. The Lindau Messenger, a courier service run by the city of Lindau, passed through here on its way to Milan, alongside mule caravans, merchants and diplomats. German director Werner Herzog filmed scenes here for his 1976 film Heart of Glass.

A staircase of 321 steps, starting at a parking area with a kiosk between the two road bridges, leads down to the narrowest point and the whirlpool. The whole gorge can also be walked on foot, using the Pùnt da Suransuns and Traversinersteg II footbridges to link the historic paths.

The rock walls display patterns of water erosion created over thousands of years, forming shapes that look almost sculptural. Visitors can spot undercuts and polished surfaces where flowing water has slowly worn away the stone.