The ability of a watch to withstand water from entering the case. Water is prevented from entering the case by silicone gaskets used to seal the caseback, crystal and, crown. For enhanced water-resistance, two gaskets (or more) are typically used on the crown, because it needs to be able to be adjusted in and out.

Common water-resistance measurements are Atmosphere, Bar, Meter, Feet (1 ATM = 1 BAR = 10 METERS = 33 FEET).