Ruinaulta, also known as the Rhine Gorge, is a canyon in the canton of Graubünden (Grisons), Switzerland, carved by the Anterior Rhine between the villages of Ilanz/Glion and Reichenau. It was formed by the prehistoric Flims rockslide, which blocked the river and eventually gave rise to the present-day gorge.

The Ruinaulta extends for about 14 kilometres and is characterised by white cliffs, forested slopes, quiet lakes, and varied habitats supporting a diversity of plant and bird life. It can be explored on foot, over water, or by bicycle, and the Rhaetian Railway passes through the gorge, with stations at Valendas-Sagogn and Versam -Safien.

Ruinaulta lies within the Swiss Tectonic Arena Sardona, which was inscribed as a UNESCO World Heritage Site in 2008.

The Ruinaulta lies between the Surselva and Imboden regions in the canton of Graubünden, extending from Castrisch to Trin along the upper valley of the Anterior Rhine (Vorderrhein ).