Water under crystal

try this link below
https://www.armitron.com/pages/warranty

The crystal is an exact fit so I would recommend sending it back to the makers to get a price for a replacement crystal or take it to a watchmaker and he will send it back for you

The most common failure of a watch to be water resistant is caused by a faulty contact between the case at an opening around the glass, crown, or pushbutton and the opening's gasket. Worn or defective rubber O-rings are often a cause of failure. Condensation forming under the crystal of a watch following a sharp temperature change (a swim after a stretch in the sun, for example) tells you to have the watch checked without delay. This can be an indication of additional moisture elsewhere inside the case. It is also the only water-tightness check a consumer can perform.
Of course non-water-resistant watches don't contain the additional seals and gaskets found on water-resistant models. Consequently, moisture-laden air can easily enter the case. Once inside, a pronounced change in temperature may cause condensation to form under the crystal. Very little can be done to prevent this. A high-quality water-resistant watch, however, properly serviced and maintained, will be sealed to prevent internal water damage and will more than outlast an ordinary watch.
To keep the watch properly sealed, replace any defective parts , such as gaskets, crystals, and crowns. Water-resistant watches should be tested for case tightness at least once a year, as well as every time the watch is opened, such as when a battery is replaced.

You can get instructions from the Amitron web site.
Copy "www.armitron.com/watch_instructions.asp" into your search engine
and you will see a list of illustrations of watches and associated
instructions.

Choose the one that looks like yours and download the PDF file.

Copy "www.armitron.com/watch_instructions.asp" into your search engine and you will see a list of illustrations of watches and associated
instructions.

Choose the one that looks like yours and download the PDF file.

Water resistant does not mean water proof. You should never wear this watch while bathing, swimming or in sauna.
Any watchmaker will be able to remove any condensation and dry out your watch - no matter you are in the U.S.A. or Romania.
Find your nearest watch repair shop and ask for help.

Rate, please.

Follow this link and find users manual for your son's watch:

http://www.armitron.com/watch_instructions.asp

Rate me, please.

WR 165 simply means Water Resistant to 165 feet. The model of your watch is stamped on the back of the watch face.

Check out this website for possible instructions, and at least they can sort of help you get started....

http://www.armitron.com/watch_instructions.asp