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
Boy seaman
…British boy sailors receiving instruction on how to use a sounding line onboard the battleship HMS Rodney during World War II A boy seaman (plural boy seamen) is a boy who serves as seaman or is trained for such service…
A sailor and a man on shore, both sounding the depth with a line