There is no such thing as a "Water proof" watch ANYWHERE. Even diver watches are rated to x meters.
Drop the highest rated watch in the world here:
The Challenger Deep in the Mariana Trench is the deepest known point in Earth's oceans. In 2010 the United States Center for Coastal & Ocean Mapping measured the depth of the Challenger Deep at 10,994 meters (36,070 feet) below sea level with an estimated vertical accuracy of ± 40 meters.
Bring it back up and see how it fares with about 11km of water pressing down on it.
"Water proof" means impervious to water, regardless of depth. This term should never be applied to any electronics or watches. (and likely very little else).