What is the term used for a deep narrow passage with rocky walls and a river running through it?

The term "gorge" refers specifically to a deep, narrow passage characterized by steep, rocky walls and typically formed by the erosion of a river over time. This geological feature can be seen in various landscapes where a river has cut through harder rock layers, resulting in the sharp, cliff-like sides that define a gorge.

A valley, while it also represents a low area between hills or mountains, is generally broader and may not necessarily have the steep walls commonly associated with gorges. A canyon, similar to a gorge, can feature large and deep formations but usually refers to wider spaces and is often associated with larger rivers. A cliff is a steep face of rock and earth that does not specifically indicate the presence of a river. Thus, the most accurate term for a deep narrow passage with rocky walls and a river flowing through it is indeed a gorge.