Different levels of water resistance for a watch are: Water-resistant 30m/50m (suitable for washing hands and light swimming) Water-resistant 100m (best for recreational swimming, surfing, and sailing) Water-resistant 200m (suitable for professional marine activities) Diver’s 100m (for scuba diving without needing helium gas) Diver’s 200m (best for scuba diving at depths without helium gas) Diver’s 300mor more (suitable for saturation diving)