Does a true dive watch need ISO 6425 certification?

Well, when I go around many watch forums, it appears that one of the most asked questions by dive watch enthusiasts is: “Does a true diver need ISO certification?” Up to now, this debate hasn’t been settled yet. What is your opinion about it?

In my point of view, a true dive watch isn’t necessarily marked as “ISO-certified”. Let me tell you the reasons why!

Firstly, what is the ISO-certification?

According to the official website of ISO:

“ISO (International Organization for Standardization) is an independent, non-governmental membership organization and the world’s largest developer of voluntary International Standards.”

As you can see, ISO’s first and foremost role is to set standards. They are not an inspector who is in charge of monitoring the testing process, it’s done by the manufacturers indeed. Therefore, if a producer claims that their products are ISO-certified, they actually mean “We’ve put each of them through the ISO standards test ON OUR OWN!” That’s it!

Two different ISO-certified dive watches could have been put through 2 total different testing procedures. That’s ok, as long as the producers can make sure their watches meet all those ISO requirements in practical use, or else they would be blamed as making false advertising claims.

What are the differences between ISO & non-ISO dive watches?

Following are some main points of the ISO 6425 standard applied to dive watches (you can check out ISO’s official website for the full version. By the way, you have to pay, it’s not free document!!!):

  • 100m minimum water resistant depth
  • Have a time-preselecting device (a unidirectional bezel or a digital display)
  • Transparent legibility at the distance of 25cm in the dark. These items must be visible in total darkness: the minute & hour hands, the tip or tail of the second hand, the lumed pip on the bezel, the digital display & the battery end-of-life indicator (if existing)
  • Thermal shock resistance
  • Shock resistance
  • Salt water resistance
  • Magnetic resistance

…And a few more criteria

You see? “True” dive watches must meet a dozen of requirements, only high water resistance rating is not enough. Each of them has to be put through a complicated testing process to make sure they satisfy all of the ISO 6425’s criteria. Thus an increase in fabricating cost is inevitable!

That’s why many reputable brands don’t implement this testing process to each of their products. They accept to mark their diver-styled pieces as “Water resistance” rather than “Diver’s”, because they know there’re many consumers who care about the price more than the guarantee. They only test a sample product, and then implement the same producing process in mass.

On the contrary, if a watch is marked as “Diver’s”, you know that the producer has tested it against the ISO 6425 standard before releasing it to market. This is the biggest difference between an ISO-certified dive watch and a non-ISO one.

Don’t mistake me! In fact, non-ISO certified dive watches can be very reliable! Lots of diving pieces from prestigious brands have never undergone an ISO6425 testing, but they still offer superb quality. As long as the manufacturing is of high standard and well-controlled, the unqualified rate is extremely low.

Rolex, the No.1 luxury watchmaker in the world, never bothers with the ISO 6425 requirements. You wouldn’t see a single line about ISO standard on their advertisements, since people know what they should expect from Rolex, their brand reputation does all the talking! Their classic dive watch, the Rolex Submariner, had already earned the trust of pro-divers long before the ISO 6425 was born.

Do you need all features required in the ISO 6425 standard?

Be honest to yourself, do you need your diver to have all of the features required in the ISO 6425? I don’t. Magnetic resistance? No, I always avoid putting my watch in magnetic field, keep it away from electric appliances! A luminous second hand to indicate your watch’s still running in the dark? No, unless I’m working on a military task, most of my diving situations are usually not a matter of life and death, my bottom time is flexible as I never dive too deep, in case my dead watch makes me miss the turning point, I still have more than enough of ascent time.

ISO 6425 is an industry standard, by following its requirements, manufacturers can make standardized fully-featured products that satisfy all of customers’ possible demands. The problem here is that we don’t always need all of these features, so why do we have to pay more to get what we don’t need?


At the end of the day, there’re only two things affect my purchase decision:

  1. The brand’s reputation: Many watchmakers claim that their dive watches are ISO-certified. I just have their words on it, a little boost in trust, of course, but the most important thing is still their reputation, no other certification is more persuasive than that.
  2. My own demands: Lots of diver-styled timepieces are being marked as “Water resistance”, they don’t claim themselves to be “real” dive watches. They might not meet some of the dive watches’ requirements, but as long as their imperfections are not a huge deal to me, they are still “true” dive watches to me!

Above is my opinion, how about yours?

Some reliable dive watches which are non-ISO (reviews):

Some affordable ISO-certifed diving pieces (reviews):

3 thoughts on “Does a true dive watch need ISO 6425 certification?”

    • Well, the Submariner is indeed a true diver’s watch, it meets all the ISO standards for analog dive watches. Rolex just doesn’t bother to tell us about it in their ads. Their brand alone is strong enough to make trust! By the way, ISO doesn’t make any test; they just suggest the standards for watchmakers to follow. At the end of the day, we still need to trust the manufacturers!

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