In 1927 Mercedes Gleitze was the first female swimmer of Great Britain to cross the English Channel. On that occasion, she was wearing a Rolex Oyster that was conceived, designed and manufactured by Hans Wilsdorf.
Even though waterproof watches had already been made in previous years, the Rolex Oyster created in 1926 was the first real watch that was impermeable to water and, especially, resistant to water pressure. Thanks to that very special ambassador — and a woman, to boot — news of the birth of this timepiece reverberated around the globe, marking a new era.
The notion of water resistance concerns the functional characteristic of the timepiece that protects it from the humidity of the environment, the pressure and also the perspiration of its wearer. Measured in bars, which indicate pressure units, water resistance is confirmed only after the timepiece has successfully passed precise tests established by the international standard ISO 22810 and is guaranteed during the entire duration of the warranty of the watch, as indicated by the brand: i.e., at least two years from the date of purchase. Traces of condensation or oxidation on the dial of your timepiece are therefore signs of a problem regarding its water resistance that should be immediately communicated to the post-sales service of your boutique or dealer.
If there is no specific indication of the brand, a waterproof watch is guaranteed at 2 bars, which corresponds to the value of the water pressure 20 meters below the surface.
But the key thing to know is that waterproof watches are not intended for sea diving because this type of use would seriously damage the movement. In that particular case – and also for athletes involved in more extreme water sports such as rafting, surfing, and wakeboarding – it is advised to choose a watch able to withstand pressures exceeding 2 bar.
People who love deep sea diving must wear a first-rate diver’s watch that can help with its indications, even in the most dangerous situations. To belong to this carefully regulated category, the diver’s watch must be equipped with precise functions and pass numerous tests to meet the criteria of the international standard ISO 6425.
Obviously in this case the minimum guaranteed water-resistance corresponds to 100 meters, but it is just one of the factors necessary for a diver’s watch. Besides ensuring resistance to shocks (certified by ISO 1413) and magnetic fields (certified by ISO 764), the watch dial must also be equipped with a unidirectional counterclockwise rotating bezel. It must have elapsed time markings (second hands, rotating disc) and a luminescent index at twelve o’clock on the bezel, with a 15 minute scale and an index every 5 minutes. Divers must be able to read the time and elapsed time markings and have a clear view of the bezel in the darkness up to a maximum distance of 25 centimeters.
Last but not least, the strap of the diver’s watch must be firmly attached to ensure its reliability and measure the time while worn snugly strapped to wrist of the diver, allowing him or her to fully enjoy the diving experience in complete serenity, even in more perilous moments.