Water resistance is a condition, not a promise forever
The original water-resistance rating assumes seals and case integrity are in suitable condition. Gaskets age, and opening, impact or prior repair can change performance. Have resistance tested by a qualified provider before swimming or diving, and after any service that opens the case.
Rinse only when the maker allows it
Salt, sweat and sunscreen can build up on a case or bracelet. Clean according to the manual and only use water if the watch's seals have been checked and the instructions permit it. Never operate crowns or pushers underwater unless the exact model's manual explicitly allows it.
Manage temperature and materials
Avoid leaving a watch in a hot car, sauna or direct sun. Leather straps are vulnerable to sweat and moisture; consider a suitable alternative strap if the design permits. Wipe the watch dry after wear and allow straps to air fully before storage.
Use a qualified service route
A sudden change in accuracy, condensation under the crystal, a stiff crown or impact warrants prompt inspection. Follow the manufacturer's service recommendations and keep service records. A watch is not a substitute for a dive computer or other dedicated safety equipment.