Measuring depths is a job that requires the use of a PLUMB, which is a tool consisting of a weight suspended from a line used to determine the depth of water or other liquids. The term 'PLUMB' comes from the Latin word for lead, as the original plumbs were made of lead. Measuring depths is an important task in many industries, such as construction, engineering, and surveying. It is also used in recreational activities, such as fishing and diving.