The term water resistance refers to the watch's ability to withstand splashes of water to varying degrees. You have to be careful when using a water resistant watch. The resistance of a watch is only an indication of how waterproof it is. If you are swimming with a watch, the movement of your arms will drastically alter the pressure that the watch is under. Or if you use your watch in a hot tub, sauna, bath or shower, the heat could cause the seals to expand. This would cause the water resistance to be compromised, making your watch less water resistant or even causing it to malfunction completely.