In 1970 OMEGA officially launched a watch that had been created to withstand the crushing pressures endured by divers working deep below the ocean’s surface. It was the Seamaster Professional 600, the so-called “Ploprof” (from plongeur professionnel – French for “professional diver”). It was among the most robust and seaworthy divers’ wristwatches ever made.

The Ploprof’s bi-directional diving bezel is released and locked by the characteristic security pusher at 2 o’clock. An automatic helium escape valve is on the side of the case at the 4 o’clock position and allows helium atoms to escape during decompression – particularly useful for divers operating from diving bells. And the Ploprof is water resistant to an astounding 120 bar (1200 metres/4000 feet).