Use these guidelines to choose the right water-resistant watch:

1. Water Resistant: Watches that are marked “water resistant” that do not specify a depth rating are not designed to be submerged below the surface of water. They are designed only to protect against accidental exposure to water.
2. 1 ATM: 10 metres/33 feet: Protected against accidental exposure to water; for example, splashes, perspiration or accidental immersion. It should not be submersed in any water.
3. 3 ATM: 30 metres/100 feet: Suitable for everyday use. No swimming.
4. 5 ATM: 50 metres/165 feet: Suitable for short periods of surface swimming. No diving or snorkelling.
5. 10 ATM: 100 metres/330 feet: Suitable for swimming and snorkelling. No diving.
6. 20 ATM: 200 metres/660 feet: Suitable for high-impact water sports and recreational scuba diving.
7. Diver: 150-200 metres/500-660 feet: Suitable for deep-sea scuba diving.

The depth specified on the watch dial represents the results of tests done in the laboratory, not in the ocean. They refer to the depth at which a watch will keep out water if both watch and the water are perfectly motionless. These conditions, of course, are never achieved in a swimmer's or diver's environment. In real life, the movement of the wearer's arm through the water dramatically increases the pressure on the watch; so it cannot be worn to the depths indicated by lab testing machines.