Water Resistance
The water resistance figure on a dial is a laboratory pressure rating, not a real diving depth. 30 meters means hand washing and rain, 50 meters adds splashes and, for some brands, swimming in shallow water, and 100 meters is what we recommend for regular swimming and the ISO 6425 floor for a certified dive watch. No rating makes a watch safe in a hot shower, bath or sauna, and no watch is truly waterproof; it is only water resistant.
Water resistance is measured under static pressure in a one-time lab test on a new watch, and the swimming you actually do adds only about 5 meters of equivalent dynamic pressure. The number on the dial reads more optimistic than real life mainly because gaskets age and thermal cycling and impacts erode the seal over the years, not because of large dynamic loads.
What the ratings mean in practice
- 30 meters: hand washing and rain, not swimming
- 50 meters: splashes and, for some brands, swimming in shallow water; not regular swimming or showering
- 100 meters: swimming and snorkeling, and the ISO 6425 minimum for a certified diver's watch
- 200 meters and above: more margin for snorkeling and free diving; for scuba, choose an ISO 6425 dive watch marked DIVER'S, a standard that starts at 100 meters
Gaskets age over the years
Water resistance depends on the gaskets that seal the case, and those gaskets harden over time. If you genuinely swim or dive, periodic pressure testing is essential. Always make sure a screw-down crown is fully closed before you get in the water.
For more, see the Water and Diving category and the Best Dive Watches Under $500 guide.
Related terms
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Frequently asked questions
Is 100 meters of water resistance enough for diving
For snorkeling, yes; for scuba, the number alone is not enough. 100 meters is the minimum ISO 6425 sets for a diver's watch, but scuba needs a watch that passed all ISO 6425 tests and carries the DIVER'S marking; an ordinary 100-meter watch is a swimming watch.
Can I shower with a 30 meter water resistant watch
It is not advised. 30 meters survives hand washing and rain, but hot water vapor and soap stress the gaskets and raise the risk of a leak over time.
How do I keep the water resistance
Close the screw-down crown before water, have the gaskets pressure-tested every few years, and keep the watch out of hot water and saunas.