What terrain feature is a low point in the ground or a sinkhole?

A depression is defined as a low-lying area in the landscape, which can often take the form of a sinkhole or pit. This geological feature is characterized by its surrounding elevated terrain, making it distinctly lower than its surroundings.

In the context of topographical mapping and military operations, understanding such terrain features is crucial. Depressions can serve various tactical purposes, such as natural concealment for troops or vehicles, and can impact movement and visibility on the battlefield.

The other options represent different terrain features: a gorge is a narrow valley with steep sides, a summit is the highest point of a hill or mountain, and a bay is a body of water partially enclosed by land. Each of these has unique characteristics that do not align with the definition of a low point or sinkhole, further clarifying why a depression is the correct choice.