A fathom is a unit of length in the imperial system and is equal to 6 feet (1.8288 meters), used especially for measuring depth of water. The 'fathom' is neither an international standard unit, nor an internationally accepted unit. Historically it was the maritime measure of depth in the English-speaking world.
So, why then '22 Fathoms Diving?'
Because 1 fathom is equal to 6 feet. 6 multiplied by 22 results in 132 feet, which is the limit for Recreational Divers. Keep in mind that the recommended limit for newly certified divers is 60 feet.
