Is my watch waterproof?
The term 'Waterproof' was used in the early 20th century, but has since been deemed misleading and has been discontinued. No watch can ever be classified as waterproof, only water resistant.
Modern water resistant watches are rated by depth; the higher the rating, the more water pressure a watch can withstand. Depths range from 30M (for basic everyday use) to 600M (for scuba diving). Water resistant watches are always labeled 'Water Resistant' on the back case. Some watches may also have their depth rating displayed on the front dial. It is strongly recommended that watches frequently used around water have at least a 100M depth rating.
It is important to note that the gaskets in a watch deteriorate over time and require regular maintenance. Most manufacturers recommend watches with a 100M depth rating or above to be resealed and tested every year or following every battery replacement (whichever comes first).