Indicating how well a watch is sealed against water, water resistance is an important feature for many of us. However, the water resistance standards can be confusing. The water resistance mark on a timepiece doesn’t necessarily indicate how far under the water you can take the watch. One reason is that your motion under the water, such as swimming motions with your hands can significantly increase the pressure the seals are under.
The International Organization for Standardization controls water resistance measurement regulations. There’s no such thing as a “water proof” watch, however watches can have a wide range of water resistancy. Below is a chart to further explain their water resistant ratings and suitable resistant activities (exposure to water).
| Water Resistance Rating |  |
 |
 |
 |
 |
 |
| 1 ATM 10 Meters 33 Feet |
X | |||||
| 3 ATM 30 Meters 100 Feet |
X | X | ||||
| 5 ATM 50 Meters 165 Feet |
X | X | X | |||
| 10 ATM 100 Meters 330 Feet |
X | X | X | X | ||
| 20 ATM 200 Meters 660 Feet |
X | X | X | X | X | |
| 30 ATM 300 Meters 990 Feet |
X | X | X | X | X | X |
| 50 ATM 500 Meters 1,650 Feet |
X | X | X | X | X | X |
| 100 ATM 1,000 Meters 3,000 Feet |
X | X | X | X | X | X |
| Rain & Splashes |
Swimming, Bathing & Snorkeling |
| Brief Immersion |
Skin & Recreational Diving |
| Showering & Shallow Water |
Professional Diving |
The ISO requires dive watches to go through a more rigorous test process (ISO 6425) to ensure they will not take on water during your diving excursion. However, it is recommended that you should have regular pressure testing done to maintain its resistance
Here’s a quick guide to determine the best water resistance for your intended use:
Scuba divers, snorkelers, and anyone who wants to be sure that they can confidently play or work in the water with no worries about their watch “taking on water”, usually pick 200 meter and above dive watches, although 100 meter watches can be used confidently for swimming and snorkeling, but not diving. 50 meter watches are great for everyday wear without worry when washing your hands. 30 meter watches are actually best exposed to only occasional splashing.
