Water Resistance
What does 200m water resistance mean on a watch?
A 200m (20 ATM) water-resistance rating means a watch is built to withstand the static pressure equivalent of 200 meters and is suitable for recreational scuba diving. The number is a laboratory pressure rating, not a depth you should actually descend to — it describes pressure tolerance, not diving performance.
Ratings are static pressure, not depth
Water-resistance figures in "meters" come from a static pressure test in a lab, where the watch is exposed to a fixed pressure with no movement. Real diving adds dynamic pressure from swimming, water jets, and temperature swings, so the printed number always carries a safety margin baked in.
This is why the ratings do not scale the way they look. A 30m watch is not "safe to 30 meters" — it is splash-resistant only. The jump from 30m to 200m is a jump between use cases, not a linear depth scale.
What each rating actually permits
30m / 3 ATM: splashes and rain only — not swimming. 50m / 5 ATM: brief shallow contact such as showering. 100m / 10 ATM: recreational swimming and snorkeling. 200m / 20 ATM: recreational scuba diving.
A watch marketed as a genuine dive watch is usually certified to ISO 6425, which requires 100m minimum plus tests for shock, magnetism, and a legible unidirectional bezel, and pressure-tests each watch to 125% of its rated depth. The word "DIVER'S" on the dial signals full ISO 6425 compliance.
Keep the rating real
Always screw down the crown fully before contact with water — an unscrewed crown defeats the seal regardless of the rating. Gaskets degrade with age and heat, so manufacturers commonly advise a pressure re-test every 1–2 years for watches used in water, and after any battery change that opens the case.
Frequently Asked Questions
Can I swim with a 100m water-resistant watch?
Yes. 100m / 10 ATM is the practical minimum for recreational swimming and snorkeling. For scuba diving you want 200m or a watch certified to ISO 6425.
Is 30m water resistance enough for washing my hands?
It is rated for splashes and rain, so incidental contact is fine, but 30m / 3 ATM watches are not meant for deliberate submersion or swimming. Avoid hot water, which degrades the seals.
Why should I not shower with my dive watch?
Hot water and steam expand the case and accelerate gasket wear, which can compromise water resistance over time even on a 200m watch. Heat, not pressure, is the usual culprit behind failed seals.
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