When you say a watch is water resistant, you are saying that water cannot break the case or the seals around the function buttons.
Water resistance is measured in still, still water.
The manufacturer says that so many meters below the surface of calm water, the water pressure alone will not break the case or the seals.
But if it were to be submerged in water, or spilled while water skiing, or found in fast moving water, the pressure of the water hitting the device would be much higher than the static pressure under which the watch was tested.

For that reason, no watch can honestly be described as waterproof.
Water is potentially dangerous, and the enormous range of its hazards cannot be addressed at reasonable cost.
The US Federal Trade Commission requires that watches sold in the US be described as water resistant and not waterproof.
This hasn’t stopped online retailers from describing their watches as water resistant because is the keyword that shoppers type into the search bar.

Whether Google search spies have registered a retail website for the keyword
then Google will only show that website to searchers who type in the search bar
But if buyers just write in the search bar, Google will only show them websites that have in them.
so if you are a retail website and you want those buyers then that is the keyword to put on your site

However, watch manufacturers require their retailers to display ATM ratings.
The standard atmosphere at sea level is 1ATM.
A watch described as 5ATM is water resistant to 5 atmospheres, or around 80 PSI. This translates into a water depth of about 50 meters.

3 ATM – Resistant to rain and splashes.
5 ATM – Swim without jumping from a diving board. No snorkeling or diving
10 ATM – All of the above plus snorkeling in shallow water. Don’t dive high.
20 ATMs: all of the above plus high diving
200 ATM – Dive watch water resistant to 6600 feet

The higher the ATM rating, the more you will pay for the watch
but to cater for hazardous events, you must purchase the highest rated ATM you can reasonably afford
If there are two devices that meet your needs, but one is rated at 10 ATM and the other is rated at 5 ATM, don’t think “I’m only going to use it for swimming so I don’t need the 10 ATM.”
Think “Anything can happen. Can I reasonably afford the best watch?”
Jumping in the pool and common water sports can take your watch (over time) just as hard or harder than deep-sea diving

The buttons of a watch are difficult to seal
The more functions there are on a watch, the more buttons there will be and the more places water can get into the movement.
Therefore, an aquatic activity watch should be a metal-backed watch with minimal functions and minimal buttons.
Do not press any button when the watch is under water.

Moisture may appear on the dial if a watch is suddenly cooled.
After a while this moisture will disappear again.
However, steam is a different matter.
Steam can get into a watch where water cannot and can cause damage.
You should not wear a waterproof watch in the bathroom or while taking a hot shower.
And if you keep the watch on while washing your hands, use cold water.