The way the water resistant is stated on a watch is somewhat misleading. A watch with a water resistant rating of 30 meters doesn't mean you can take the watch under water up to 30 meters and expect it to still be water resistant. Water resistant rating of a watch is obtain through a laboratory test that test the watch's ability to withstand a static pressure for a short period of time at the stated depth. Actual water pressure on a watch during use under water is greater than the static pressure.

Different manufacturers have different recommendations on water resistance usage. In general they can summarized as follows:

Water Resistant 30 Meters  - Splash resistant (e.g. rain, washing hands, etc.)

Water Resistant 50 Meters - Suitable for still water activities

Water Resistant 100/200 Meters - Suitable for water sports

Water Resistant 200+ Meters - Suitable for diving

Despite the manufacturers' recommendation, in practice, we see that it is best not to submerge a watch in water unless it has a water resistant rating of at least 100 meters. We do not recommend taking any watch with a leather band into water as it will cause deterioration to the band. If you plan on using your watch is the ocean (salt water), the watch should be thoroughly rinse off with fresh water after use. There are many other factors that can affect the water resistant of a watch including sudden temperature change (e.g. stepping into a sauna) and sudden pressure change (e.g. plunging into the water). It is important to remember that the water resistance of a watch will deteriorate over time as the gaskets that keep the water out aged. If you will be using your watch under water, then the water resistance of a watch should be tested each time you have a battery change or have service done on the watch.