The Blancpain Fifty Fathoms was launched in 1953 as a tool for military combat divers, and its name refers to 50 fathoms, about 91 metres, the depth a combat diver was then believed able to reach. An early example from around 1953 sold by Phillips has a 41 mm stainless steel case with a screw-down case back and a double O-ring crown system, an original Bakelite rotating bezel, and a black lacquered dial with large luminous numerals and markers, centre seconds and gilt printing. Early pieces also carry a “Luxor” minute hand shaped like an obelisk. It is powered by the self-winding AS 1361N calibre with 21 jewels, chosen so the diver would rarely need to touch the crown, and the case was protected against magnetic fields.

The watch was developed after Captain Robert “Bob” Maloubier and Lieutenant Claude Riffaud, who had founded a French combat swimmer unit, found nothing on the market able to time dives, oxygen reserves and underwater navigation. They approached Blancpain CEO Jean-Jacques Fiechter, himself a diver, and Maloubier sketched the first design. Fiechter added the features that defined the modern dive watch: a unidirectional bezel that could not be turned by accident, a screw-down back, an automatic movement, antimagnetic protection and, on some versions, a humidity indicator at six o’clock that turned pink if water entered. Jacques Cousteau’s divers wore it in “The Silent World,” which won the Palme d’Or and an Oscar in 1956, and the watch was later adopted by other forces, including the US Navy, in versions such as the Milspec.

The Fifty Fathoms is widely regarded as one of the founding modern dive watches; Blancpain presents it as the first dive watch on the market, a year before the Rolex Submariner. Original military and early civilian pieces are keenly sought: the 1953 example above sold for 30,000 dollars at Phillips New York, a circa 1955 piece retailed by Lip made CHF 42,840 at Phillips, and a circa 1970 Milspec I fetched CHF 40,000 in 2017. Phillips singled out that watch’s original Bakelite bezel as unusually well preserved, without cracks. The 1953 model is no longer produced, but the Fifty Fathoms remains one of Blancpain‘s main collections, with modern automatic, chronograph and Bathyscaphe versions.