Depth gauge
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A depth gauge is an instrument for measuring depth below a vertical datum or other reference surface. They include depth gauges for underwater diving and similar applications. A diving depth gauge is
US Marine diver with a diving watch and an analog depth gauge
A digital depth gauge combined with a timer and temperature display, also referred to as a "Bottom timer"
Dive computer showing depth display
Pressure gauge on Siebe Gorman manual diver's pump, indicating delivered pressure in pounds per square inch (black) and feet sea water (red)
Depth sounding
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Depth sounding, often simply called sounding, is measuring the depth of a body of water. Data taken from soundings are used in bathymetry to make maps of the floor of a body of water, such as the seab
Depth gauge
…physical probe to measure the vertical distance from the reference surface to the bottom or other relevant point, such as a dipstick, sounding pole or sounding line, or use light or sound emitted from a known distance from the surface and reflected by the bottom to calculate depth based on elapsed time of travel…
A sailor and a man on shore, both sounding the depth with a line
Lead and line sounding
Sounding leads
Edward Massey's sounding machine