Watches are classified by their degree of water resistance, which roughly translates to the following (1 meter = 3.281 feet):
| Water resistance rating |
Suitability |
Remarks
|
| Water Resistant 30 m or 50 m |
Suitable for water related work and fishing. |
NOT suitable for swimming or diving.
|
| Water Resistant 100 m |
Suitable for recreational surfing, swimming, snorkeling, sailing and water sports. |
NOT suitable for diving.
|
| Water Resistant 200 m |
Suitable for professional marine activity and serious surface water sports. |
NOT suitable for diving.
|
| Diver's 100 m |
Minimum ISO standard (ISO 6425) for scuba diving at depths NOT requiring helium gas. |
Diver's 100 m and 150 m watches are generally old(er) watches.
|
| Diver's 200 m or 300 m |
Suitable for scuba diving at depths NOT requiring helium gas. |
Typical ratings for contemporary diver's watches.
|
| Diver's 300+ m helium safe |
Suitable for saturation diving (helium enriched environment). |
Watches designed for helium mixed-gas diving will have additional markings to point this out.
|
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