New Arrival: 1958 Longines Nautilus Skin Diver T910 (ref. 6921)

Certainly in the mid-fifties it was common to see actual divers with harpoon guns on the front of dive equipment brochures from the likes of Aqualung. So I guess it was one of a few obvious choices when companies decided to put some kind of logo on the their dive watch casebacks. As far as I know the Longines and LeCoultre DSA were around the same period (late fifties), but I think perhaps the Longines was out slightly earlier. Maybe it was the first.

missing harpoon...

Something like this...