Standing on the Roman bridge, and looking upstream.
The Canyon itself, which ends at the Roman bridge, is 14 km long; as such it is the longest in Turkey. In summer, it is visited massively by rafting groups (reportedly up to seven thousand people each day).
On the left side of the bridge, in upstream direction, a narrow (not paved) walking path runs for some 500 m into the Canyon, slowly descending to the water level, where it ends. The walk offers a good quick impression of the greatness of this natural phenomenon.

Correspondent: J.M.Criel, Antwerpen.
Sources: Personal visits to Köprülü Kanyon and Selge/Altınkaya (1992 – 2004) & Vikipedia.