A "deep hole" refers to a cavity or excavation that extends significantly below the surface of the ground. These holes can be created naturally, such as sinkholes or deep caves, or artificially, like wells and mining shafts. The depth of a hole can vary widely, but it is generally considered "deep" when it reaches several meters or more. Deep holes can serve various purposes, including water extraction, geological research, or waste disposal. They can also pose safety risks, such as falling or collapsing, and may require proper signage and barriers to prevent accidents. Understanding the characteristics of deep holes is important for both safety and environmental management.