Houston’s Leader in Rolex Watches

Top 5 Components of a Dive Watch


May 19, 2017



 As you sit by the pool admiring your new Blancpain 50 Fathoms Bathyscaphe, first appearing in 1952 as a collaboration by Blancpain, uniting the French Navy and the secret services, you wonder if your 50 Fathoms will see the same sort of underwater action as it’s forbearers encountered. And should such a scenario ever occur, what exactly makes your watch qualify for extreme adventures under the surface.

 This has been a question concerning dive watches since François Borgel came up with the idea in 1903 of having the case back and front threaded so the two could be screwed together to create a tight seal. That along with Rolex’s Hans Wilsdorf vision of the need for a screw down crown to further waterproof the case, giving birth to the first truly water resistant watch and the Rolex Oyster case.

So, let’s take a look at the Top 5 components you need to be able to boldly proclaim your piece as a dive watch.

1. Case

The watch case is the starting point of water resistance for any dive watch worth it’s mettle under the waves. Case form and materials above all else are the main factors in a watches depth rating. In 1990, the ISO or International Organization for Standards issued the standards and testing practices required to gain dive watch status. Case testing requires the case to be submerged in sodium chloride for 24 hours after which it is inspected for corrosion or other case imperfections caused by the submersion. In 1996, the same aforementioned organization issued ISO 6425 concerning water resistance ratings and dive watch features. According to ISO6425 a true dive watch must withstand diving at depths of at least 100 meters with a system in place to control the time. ISO6425 requires diving watches to be tested in static or still water under 125% of the rated water pressure. Unfortunately, the ISO testing is voluntary and involves costs, so not all manufacturers are willing to participate. A quick side note, only those watches tested and meeting ISO dive watch standards are allowed to put “diver” on the dials of their products.

2. Bezel

Next to keeping water out of the watch so it remains functional, the bezel is an extremely important component of a serious dive watch, at least before the advent of computer aided diving, which by all rights would end this article in its tracks. Once again according to ISO standards, a true dive watch must be equipped with a device that allows the diver to select a period of time up to 60 minutes with markers every 5 minutes. This can be in the form of a uni-directional bezel or a digital display. The device must be protected from accidently moving from its position. This is where the uni-directional movement on the bezel comes into play. If it is inadvertently moved out of position it will only result in you surfacing sooner than desired but with plenty of air left in your tank. Some watches have an inner rotating bezel under the crystal with a locking device on the crown. But in most instances the uni-directional bezel is the application of choice.


“Clearly” is one of the ISO’s favorite words and when it comes to dials, if you want to be a dive watch, then the dial better be clear of clutter and easy to read. Non-negotiable. Dive watches generally have only three hands which removes congestion and gives the diver the best chance of assessing the time in murky waters. Two elements that ensure legibility at night are luminous hour markers and hands. We have come a long way from the radioactive luminous paint used in days gone by. Super-Luminova a non-radioactive luminescent pigment is most often used in the industry today, although many manufacturers have their own proprietary formulas. One of those methods in use, most notably by Ball Watches is their Self-Powered Micro Gas Tubes with a stated lifetime of 25 years. Again, according to ISO standards, you must be able to tell if the watch is running and this is achieved by placing luminous material on the second hand while battery operated watches must have a low-battery indicator on the dial. Each of these must be visible at 25 cm, or about 10 inches in the dark.

4. Helium Release Valve

The helium molecule is extremely small and under the right circumstances, like high pressure, helium can sneak past the seals of a watch where larger water molecules would never be able to penetrate. Once that happens the helium can build up under all that external pressure until it has to be released, often in the form of the crystal blowing off. To prevent that, the valve automatically depressurizes the watch upon a return to sea level pressure. We must note that this feature is only put to use in instances of divers temporarily living in deep water habitats.

5. Strap/Bracelet

Now that you have acquired all the right parts for your watch to withstand the rigors of the sea, you need a way to securely attach it to your wrist to make sure that it returns intact, to the surface with you. There are a number of ways to achieve this goal with plenty of style. The ISO has requirements dealing with external forces against the watch and one such pertains to the spring bars. With the strap in the closed position the inside of the strap is subjected to an outward force of 200 newtons in each direction or about 45 pounds of force on each spring bar. Other than that article of the standards, the field is pretty much wide open, with waterproof capabilities always on the mind of course. Rubber straps and dive watches will forever be synonymous. Ribbed rubber straps even more so. Not only do they offer a masculine look, but over a wetsuit as the diver descends and the pressure increase the strap contracts to compensate for it. Nato straps are one of the oldest, most easily adjustable, durable and cost effective straps on the market. Nato straps were made famous by James Bond of 007 lore and used by military forces around the world. They are still a popular choice on more than just dive watches. Stainless steel bracelets have always been a popular choice among dive watch enthusiasts, adding at times just enough elegance to bridge the gap between beach and boardroom. Think Rolex Submariner with its iconic Oyster Bracelet. Stainless steel bracelets also come with wetsuit extensions such as the Rolex Sea Dweller and Sea Dweller Deepsea. One of the most, I think ingenious designs to come on the market, or better stated return to the market, is the Tudor Pelagos with its auto adjusting spring mechanism which allows the bracelet to be adjusted during the dive. The spring allows the bracelet to contract when it is subjected to greater depths and expand when the pressure decreases upon ascent. There are many other strap and bracelet options like the iconic stainless steel mesh style bracelets, Kevlar, and new Cardura high performance fabrics and sailcloth to name just a few.

So, there we have a brief and basic background explaining some of the guidelines used to make sure that when you buy your next dive watch it meets your adventures expectations.