Ratings assume new gaskets and an undamaged case. After any case work — crystal, crown, caseback — pressure test before the watch goes near water again.
- 3 ATM — splashes and rain only, no submersion.
- 5 ATM — hand washing, light rain, no diving or swimming.
- 10 ATM — swimming and snorkelling.
- 20 ATM+ — recreational scuba diving (check for an ISO 6425 dive-watch rating specifically, not just the depth number).