Fifty Fathoms

The Fifty Fathoms was developed as a watch for timing dives. Blancpain dates its introduction to 1953. Large luminous markings made the time visible, while a rotating ring around the face let a diver compare the minute hand with a starting point.

Jean-Jacques Fiechter, who helped lead Blancpain and dived himself, worked on the watch's seals and protection against accidental bezel movement. French combat-swimmer officers Robert Maloubier and Claude Riffaud also needed a reliable underwater watch. Their requirements connected the developing instrument to military diving.

Later watches kept the elapsed-time ring while changing its construction. The modern collection introduced in 2007 used a large 45 mm case and an automatic movement with a five-day power reserve. A sapphire cover over the luminous bezel scale gave it a rounded, glassy surface.

The family expanded into different metals, dial colors and attachments. Blue titanium versions look quite different from the early steel watches, even though the minute hand and timing scale still explain their purpose.

The newer 5010 reduces the case to 42.3 mm; the earlier 5015 retains the larger outline. A shared name connects them to the original instrument, but it does not make their dimensions or mechanisms interchangeable. The most persistent feature is the one the diver would have needed to read: minutes already elapsed.