In the sixties the quartz watches did not exist. All models manufactured at that time were provided with mechanical winding or self-winding automatic movements.
The first Aquastar diving watch, called BENTHOS 500, was waterresistant up to 500 meters. This was a real performance that was possible due to a new technology which consisted in the development of round o'rings. Before, the use of flat o'rings didn't allow to obtain a significant water resistance.
To test the water resistance of a model at different depths, the manufacturer had to embark on a boat and fix the watch at a fishing wire which they immerged into the water, noting meter by meter the depth reached and to what extent the components resisted successfully the pressure of the water.
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