“It says 300 metres — can I swim with it?” The number on the dial describes what the watch survived when it was new and sealed in a laboratory. What matters on your wrist is the condition of a few small rubber gaskets, and whether the crown is screwed down. Here is how water resistance actually works.
What the depth ratings mean
- 50m: splashes and handwashing. Not for swimming.
- 100m: swimming and snorkelling — most Datejust, Oyster Perpetual, Explorer and Yacht-Master models.
- 300m: the Submariner — recreational diving and anything shallower.
- 1,220m / 3,900m: Sea-Dweller and Deepsea — saturation-diving territory, far beyond civilian use.
These are static pressure ratings, not activity guides. Diving into a pool or a hard swim stroke creates brief pressure spikes far higher than depth alone.
The screw-down crown is everything
An Oyster case is only sealed when the crown is fully screwed down. A crown left unscrewed — or not tightened after setting the time — turns a 300m diver into an open tube. Make this a reflex: after setting, always screw the crown home before the watch goes near water. On chronographs, never operate the pushers underwater.
What actually kills water resistance
- Age: gaskets harden and shrink over years whether worn or not.
- Heat: saunas, hot tubs and hot showers expand metal and degrade seals — the fastest way to let moisture in.
- Chemicals: soap, shampoo, perfume, chlorine and salt attack rubber. Rinse with fresh water after swimming, especially in the sea.
- Impact: a knock can unseat a gasket invisibly.
Assume nothing on a pre-owned watch
Unless a watch has been pressure-tested recently, treat it as not water resistant, no matter what the dial claims. Testing is quick and inexpensive; a movement ruined by water is neither. If you swim regularly, test annually.
If moisture appears
Condensation under the crystal is an emergency. Do not wear the watch, do not try to dry it with heat, and get it to a watchmaker immediately — corrosion inside a movement begins within days and turns a routine service into an expensive repair.
Water resistance checklist
- Know your model’s rating and respect it.
- Always screw the crown fully down before water.
- Avoid saunas, hot tubs and hot showers.
- Rinse with fresh water after sea or pool.
- Pressure-test annually if you swim; always test a newly bought pre-owned watch.
- Any condensation = stop wearing it and see a watchmaker now.
How GrecoWatch can help
GrecoWatch is an Athens-based luxury watch specialist and a Chrono24 Trusted Seller. Our certified master watchmaker has over 50 years of experience, including years working for Rolex.
Every service we carry out is covered by a written two-year warranty and performed using original parts only. We provide a free written diagnostic and transparent quote before any work begins.
Spyrou Merkouri 4, Athens — appointments on +30 697 546 1445.
Frequently Asked Questions
Can I shower with my Rolex?
We advise against it. Hot water and soap degrade gaskets faster than anything else, and the benefit is zero. Take it off.
Is a 100m watch safe for swimming?
Yes, if it is in good condition with a screwed-down crown and recently tested seals. 100m is designed for swimming; it is not for diving.
How often should water resistance be tested?
Annually if you swim with the watch, and always before first use of a pre-owned watch. Testing is inexpensive relative to water damage.
My watch has condensation inside — what now?
Stop wearing it and take it to a watchmaker immediately. Do not apply heat or rice. Fast action can prevent corrosion from becoming permanent damage.
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