Place several drops of mask defogger on the inside of the mask’s lenses.
Rub the defogger solution around the lens with your fingers.
Rinse the mask several times in fresh water, enough to remove large drops of the solution, but not so much that you wash away the substance entirely. A thin film of defogger solution should remain on the lens.
Rinse your mask thoroughly in warm soapy water to remove salt water, sand and other particulates that may have gathered in your mask while you were in the water. Even if you were snorkeling in freshwater or in a swimming pool, you must rinse the mask thoroughly when you get out of the water.
Rinse the mask thoroughly with clean water to remove any traces of the soap.
Dry the snorkeling mask thoroughly with a soft towel. Bacteria can grow more easily on a mask if you leave it damp. Place the mask in a sturdy storage case for protection.