In fact, I just started to study the origin of aquanaut after acquiring this beauty and found the following from the blog of acollectedman:
In Volume 4 of the Patek Philippe Magazine. Thierry Stern himself is quoted, describing the origins of the brand’s second sports watch. As he puts it, it was intended as “something wearable, not for an evening reception, but for action. It was to be given to the best officers in the army, so the design needed to remind you of something military.”