unit:FATH

A fathom = 1.8288 meters, is a unit of length in the imperial and the U.S. customary systems, used especially for measuring the depth of water. There are two yards in an imperial or U.S. fathom. Originally based on the distance between the man's outstretched arms, the size of a fathom has varied slightly depending on whether it was defined as a thousandth of an (Admiralty) nautical mile or as a multiple of the imperial yard. Abbreviations: f, fath, fm, fth, fthm.