Without a doubt one of the most well-known diving watches out there.

A fathom is a unit of length used to measure the depth in water. Fifty fathoms is 91.44 meters deep.
In 1953, the introduction of the Blancpain Fifty Fathoms, marked the beginning of a new era. 1950 was a decade that stood for discoveries and explorations. Mankind explored the highest summits in the world but also the deepest parts of the ocean. These men needed proper tool watches. The French commando frogmen asked several watch brands to make them a dive watch. None of the brands took interest to actually produce such a watch except for one brand. Blancpain created the first dive watch commissioned by the frogmen. When this watch finally hit the market, not only the frogmen, but also many other divers, underwater scientists and photographers who explored the beauty of the oceans, adopted this watch as one of their necessary tools. Blancpain put itself on the map with this waterproof - which is quite normal nowadays, but was actually quite special then - automatic wrist watch named the Blancpain Fifty Fathoms.

Its design is simple. Function over fashion. It measures 42 mm in diameter and has a rotatable, ribbed bezel with a bakelite insert and clear Arabic quarters and hour markers. When it comes to the dial, there were various versions: the first batches had a humidity indicator above the 6-hour position. This iteration right here is approximately from 1958 and probably one of the most sleek designs out there.

As you may notice the fine line that says 'LIP' above Blancpain on the dial, a French retailer. In 1953, Blancpain wasn't really known in France but Blancpain's management was pretty close to Fred LIP, who was interested in selling the watch in France under the brand LIP Blancpain. An agreement was signed in 1954 and allowed LIP to market the Fifty Fathoms through its 2,000 shops with their name on the dial. It ended in 1957, when Fred Lip launched his own sportswatch: the LIP Nautic. Not only was the dial branded with 'LIP' but also the anti-magnetic cover that sits above the movement, caliber AS 1700/1701. And as you can see, the rotor bears the name as well.