Water Resistant 30 Meters / 3 Atmospheres / 3 Bar. If your watch claims to be water resistant to 30 meters, it actually means it's just splash resistant. It does NOT mean the watch will be fine if you bring it 30 meters below sea level.
30m, 3 atm = Splash resistant. Ok for rain, hand washing, other occasional contact with water. 50m, 5 atm = Suitable for swimming, fishing, other outdoor activities. 100m, 10 atm = Suitable for snorkeling and other prolonged contact with water, but not for scuba.