The dive watch segment is perhaps one of the most crowded and competitive in the watch industry. But how did these serious tools that play a significant role in keeping recreational and commercial divers safe become such a voluminous segment of the watch market?
The transitional from safety equipment to fashion statement was surprisingly rapid. A large part of the initial popularity of the watches can be attributed to famous film stars or adventure pioneers, who could be seen sporting the watches. Diver's watches were perhaps the first category of watches to benefit from ambassadorships that now underpin a huge part of a watch's presentation to the public.
The first commercially available watch with true water resistance was the Rolex Oyster case, released in 1926. This began the emergence of dive watches for the everyday wearer. The Oyster case featured a screw-down crown and case back, and a securely sealed crystal. To prove the watch's prowess, Hans Wilsdorf, the founder of Rolex, asked Mercedes Gleitze to wear a Rolex Oyster around her neck as she attempted to swim the English Channel for the second time that year. Although she failed to cross the Channel on that occasion, her immense resilience to the cold inspired onlookers and took away any questions that she held the world record for the feat. Meanwhile, the Rolex Oyster around her neck continued functioning perfectly, finishing the swim in good order without allowing a single drop of water to enter its housing.
Ten years later, Panerai produced a diving watch prototype for the Italian Navy. This prototype would go on to become the Radiomir, a model still in Panerai's dive-centric collection. At 47mm wide, these watches were enormous by mid-20th century standards (and still thought of as large today). The name derived from the radium lume used on the dials to facilitate reading in low light conditions. While radium is no longer used in watchmaking, due to its radioactive properties, many brands now used a cream-colored luminant known as faux-radium to evoke memories of these pioneering timepieces.
The 1950s saw an explosion of interest in the field of dive watches, as well as the emergence of many watches that are now seen as classics. The Rolex Submariner (1953), the Blancpain Fifty Fathoms (1953), Breitling Superocean (1957), and the Omega Seamaster (1957) debuted in this decade. The following two decades saw many advancements in quality and aesthetics.
Many thought the quartz crisis of the 1970s would put an end to the era of the mechanical dive watch. That was not to be the case, however, as an unforeseen resurgence in interest in mechanical watches towards the end of the '80s breathed new life into the industry.
As watchmaking took strides to redefine the expectations of a wristwatch during the 1990s, ISO (the International Standards Organisation) developed a new set of stringent criteria that a watch must meet for it to be considered a true dive watch. The ISO standard was filed under the number 6425 and supersedes the previous standards outlined in 1984.
ISO 6425 remains the benchmark for all Diver's watches today. One key requirement of this standard is reliability underwater. Watches are submerged to a depth of 30±2 cm for 50 hours at 18 to 25°C. The minimum standard of water resistance for a watch to be certified is 100 meters, which is also expressed as 10 bar, or 10 ATM, which stands for “atmospheres”. A “bar” or “ATM” rating is ten times less than the water resistance in meters.
Condensation tests are also carried out at this time. To carry out a condensation test, the watch is placed on a heated plate and warmed for between 10 and 20 minutes to between 40° and 45°C. A drop of water is then placed on the crystal and left there for one minute before being wiped away. If any condensation appears on the inside of the watch, it will fail the test.
In addition to a sufficient level of water resistance, the watch must feature a time-preselecting device. In mechanical watches, the most common time-preselecting device is a unidirectional rotational bezel with a minute scale running from zero to 60 minutes (with five minute increments clearly marked). These bezels are used by divers to accurately gauge how long they have been underwater, and therefore how much oxygen they have left before they must surface. To use the bezel, the diver aligns the luminous marker at 12 o’clock with the minute hand. The minutes elapsed since submersion can then be read directly against the bezel. It is essential the bezel only turns in one direction (anti-clockwise) so the time underwater cannot be accidentally lengthened should the bezel sustain a knock or accidental manipulation.
In addition to a luminous 12 o'clock market on the bezel, so too must the hands be visible from 25cm in the dark. The seconds hand (or disc) must be at least partially lumed so it can act as a “running indicator” while submerged. This is so that it will be clear to the diver should the watch stop while in use.
It is also important that the watch continues functioning despite sustaining shocks or being subjected to magnetic fields.
Several other tests are performed to ensure optimal functionality and absolute confidence in the watch’s ability to aid the diver during their dive. Should a watch pass all of these tests it will be awarded the ISO 6425 and the makers will be at liberty to add the words “Diver’s Watch” or “Diver’s” followed by the number denoting the depth to which the watch has been tested (for example, Diver’s Watch 500M). This marking distinguishes the watch as a tool of superior quality and guarantees it is fit for purpose.