Rolex entered the diving watch into pop culture when the Submariner was placed on Jacques Cousteau’s wrist in his Academy Award winning film, The Silent World, and Sean Connery’s wrist in the first James Bond adaptation, Dr. No. The U.S. Navy gave it’s unofficial stamp of approval to the Rolex (as well as the Blancpain and Encicar Sherpa Diver 600) in a 1959 evaluation report of commercially available watches that met underwater specialty needs versus the Bulova U.S. Navy Submersible Wrist Watch, which was under development (and was not yet as good as these other options).
Somewhere along the line, the dive watch became the de facto manly man’s watch. In 1995’s Goldeneye, Omega became the official watch of the Bond franchise, and an Omega has been on the character’s wrist since then. Omega has released six 007 themed watches to date, tied to the movie releases and the anniversary of the franchise. But machismo aside, why do we need these increasingly heavy, large and feature rich watches? Who needs a helium release valve? Who needs 1,000 meters of water resistance? The answer to both of these is: technical and commercial divers, and even then, only those that wear a wrist watch while diving.
Helium is a tiny molecule of gas that makes up an equally tiny percentage of the air that we breath. But for deep sea (not recreational SCUBA) and commercial divers, helium can become a major component of the gas that they breathe. As you dive deeper, and stay down longer, oxygen actually become toxic and the accumulation of nitrogen will do some really nasty things to our bodies, so we need to replace these gasses with others that are safe to be in what we breathe. Helium is one of these other gasses that can be blended with oxygen to make it safer to work for extended periods at extreme depths. But since helium is such a small molecule, it may get into machinery (like watches) that are designed to keep out larger molecules, like water. If helium accumulates in the watch under pressure, as the watch comes up, the helium may expand and blow the crystal off the watch. This is a pretty effective way to kill your expensive diving watch. So if you dive on Heloix or Trimix, and you wear a watch exposed to the water, you should have a helium escape valve. For the rest of us, it is a little bit unnecessary.
But what about that 1,000 meters of water resistance? Also a bit of an overkill. Deep diving is a very technical endeavor requiring highly specialized training and a lot of equipment and support. It is not something that you casually decide to do. The number of people who have been to 240 meters on SCUBA (military not included) is on par with the number of men that have walked on the moon. For recreational divers, advanced diving is considered up to 100 feet and deep diving is up to 130 feet, or 40 meters. Of course, you may go deeper as an advanced diver, I have, but not by much, and not for long. The Mount Everest of borderline recreational diving is probably the wreck of the Lusitania, sitting in almost 100 meters of water, still a far cry from the depth rating of many < $1,000 dive watches.
So, if 1,000 meters of water resistance is overkill, and the vast majority of us will never need a helium release valve, what does one need in a dive watch? Well, a watch that is either certified under ISO 6425, or at least meets the same criteria, is an excellent starting point. Even if you never dive below 100 feet, having a watch rated to 300 feet gives a nice sense of security in case you do go a bit deeper, or if you exert pressures on your watch in the course of moving it about underwater that exceed your actual depth. A visual indicator that the watch is running (like a second hand, especially on a mechanical watch) is essential, as would a power reserve indicator for a battery operated watch. A unidirectional rotating bezel is a good idea, maybe you want to time a safety stop or time a leg of a swim for navigation. Luminous hands and markings are important, light falls off rapidly with depth, even in tropical waters. All of this should be standard on a dive watch, and are the backbone of what is called for in ISO 6425.
Most divers are going to wear some sort of thermal protection, either a wetsuit or a drysuit, and these add bulk to the arm, so a way to easily expand the length of the strap or bracelet is very helpful. With a strap, you can always just adjust it larger; with a bracelet, adding and removing links is a bad idea, so an expandable clasp is a great feature. The Glidelock by Rolex (above) is one example, but there are lots of variations on this type of expansion system. With rubber or silicone straps, there is sometimes a slight springiness built into the strap, which allows the strap to compensate for the decrease in a wetsuit’s thickness as it is compressed with depth. On a bracelet, a secondary clip to lock the clasp closed is also something I look at as a must-have feature.
So what else do you need in a dive watch? The short answer is, whatever else you want. I like titanium watches, especially to cut down on the heft of these larger watches, so I would consider that a real plus. I am also intrigued by internally rotating bezels, as long as the rotating mechanism allowed their use underwater (I do snorkel and swim with my dive watch, even if I don’t dive with it). I prefer a strap to a bracelet, so a quick change pin with both a leather and silicone strap would be a nice option for me. I don’t tend to use the date function, so unless it were some variation on a big date or a cyclops, a date wheel is not essential for me, but it may be for you. And if you really want a watch that has been down to almost 11,000 meters, don’t let me talk you out of it. Just don’t expect me to believe that you need a watch that robust for your next dive vacation.