How should I care for my water-resistant watch and what should I check?

Before using your watch, carefully read and understand the instruction manual to use it properly.
Also, carefully save the instruction manual, and refer to it as necessary.

1. Periodic replacement of gaskets is recommended.
   The gaskets used for the case back, crown, glass, etc., of a water-resistant watch prevent the entry of moisture, dust, etc., from the outside and protect the functions of the watch. With longtime use, the gaskets are affected by perspiration and moisture, so that their elasticity may deteriorate or they may become brittle and easy to cut. Therefore, it is recommended that you request to replace the gaskets during battery replacement or periodic checks.
2. In the event that water has entered into your watch, immediate repair is required.
   In the event that water has entered into your watch, do not use it as it is but have it repaired immediately. The entry of water inside your watch will cause damage to the internal mechanism, precision electronic components, dial, etc.
3. Do not operate the crown and buttons when moisture remains.
   Operating the crown and buttons when moisture remains may cause the moisture to enter into your watch, resulting in poor water resistance.
4. After swimming in the sea, thoroughly wash your watch with fresh water.
   After swimming in the sea, thoroughly wash your watch with fresh water, and then completely wipe it to prevent it from rusting.
5. For repair or battery replacement of a diver's watch, contact your distributor or a watch specialty shop.
   Do not use a water resistant watch for air diving (for shallow-water diving) as a watch for mixed-gas diving (for deep-sea diving).
   Operate and use each water resistant watch according to application only as specified.
   
   A diver's watch should always be checked by using a special-purpose testing machine on water resistance, etc.
   
   In particular, the time for battery replacement should be checked on a routine basis to prevent the watch from stopping due to battery exhaustion during diving.
   Use of a diver's watch for diving requires strictly carrying out before- and after-the-fact checks by the methods specified in the instruction manual, and also sufficient background knowledge, safety education, and diving training.
   

Since there is also a separate considerations by product, For proper and safe use, read instruction manuals carefully before using products. In addition, keep the manuals handy for easy reference.