A BAR is a unit of air strain measured in kilograms per sq. centimeter. 10BAR is roughly equal to 100 meters of water strain, not precise water depth. In a watch that’s 100 meters water-proof, it’s secure to be out within the rain, wash your arms, swim, and snorkel. It shouldn’t be used for SCUBA diving, showering, or in a sizzling tub. In sizzling water, the steel of the watch case will increase quicker than the rubber O-ring gasket (that retains water out) and can permit water contained in the case. I hope this helps.