A depth gauge is a tool used to measure the depth of a hole, cavity, or underwater feature. It typically consists of a graduated scale and a probe that can be inserted into the area being measured. Depth gauges are commonly used in various fields, including construction, engineering, and marine exploration, to ensure accurate measurements. These devices can come in different forms, such as digital or mechanical, and may be designed for specific applications, like measuring the depth of water in a lake or the depth of a borehole. Accurate depth measurement is crucial for safety and precision in many projects.