FAQs

Water Resistance Classification

Watches are classified by their degree of water resistance, which roughly translates to the following (1 meter ≈ 3.28 feet):

Water resistance rating Suitability Remarks
Water Resistant or 50 m Suitable for swimming, no snorkeling water related work, and fishing. NOT suitable for 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 suitable for saturation diving. 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 suitable for saturation diving. Typical ratings for contemporary diver's watches.
Diver's 300+ m for mixed-gas diving Suitable for saturation diving (helium enriched environment). Watches designed for mixed-gas diving will have the DIVER’S WATCH L M FOR MIXED-GAS DIVING additional marking to point this out.

Note: The depth specified on the watch dial or case represents the results of tests done in the lab, not in the ocean.

Some watches are rated in bars instead of meters. Since 1 bar is the approximately the pressure exerted by 10 m of water, a rating in bars may be multiplied by 10 to be approximately equal to that based on meters. Therefore, a 20 bar watch is equivalent to a 200 meter watch. Some watches are rated in atmospheres (atm), which are about 1% greater than bars. In the United Kingdom, scuba divers and others often use the word atmosphere interchangeably with bar (1 atm = 1.01325 bar, or 101,325 Pa).

Taken from wikipedia.com.