Here's why:

* Carved by water: Canyons are formed by the erosive power of rivers over millions of years. The water cuts down through rock, creating a deep, narrow gorge.

* Deep: Canyons are characterized by their significant depth, often hundreds or even thousands of feet deep.

* Ditch: While not the most common term, a ditch can refer to a long, narrow trench, which describes the shape of a canyon.

While other possibilities exist, such as:

* Gully: A small, shallow ditch carved by rainwater.

* Ravine: A narrow, steep-sided valley, often with a stream at the bottom.

A canyon is the most likely answer based on the combination of "deep" and "carved by water".