Fathom Fathom A fathom is a unit of length in the imperial and the U.S. customary systems equal to , used especially for measuring the depth of water. There are two yards (6 feet) in an imperial fathom. Originally the span of a 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. Formerly, the term was used for any of several units of length varying around . The name derives from the Old English word "fæðm", cognate
One Fathom Bank Lighthouse One Fathom Bank Lighthouse The One Fathom Bank Lighthouse ( or ) refers to two offshore lighthouses in the Strait of Malacca, specifically, on a shoal within Malaysian waters, dubbed One Fathom Bank (Permatang Sedepa), off the coast of the state of Selangor. The One Fathom Bank station was originally served by a lightship stationed in 1852 before a permanent screw-pile lighthouse was built in 1874; the lighthouse has since been replaced twice over the course of its service, in 1907 with a concrete pile lighthouse, and in 1999 when a larger modern counterpart was built parallel to the 1907