A fogged snorkel mask is annoying: Treading water while attempting to clear the haze takes the fun out of diving. Fogging occurs when water vapor condenses because of the temperature difference between the outside and inside surfaces of the mask lens. Taking preventive measures before taking the plunge means you can spend more time with your head in the water than out of it.
Buy a mask that fits your face properly to prevent water leakage, which can cause fogging. Hold your breath, position the mask and press it slightly into your face. Remove your hands from the mask without inhaling through your nose. If the fit is right, the mask will stay in place without any help from you. Because more skirt in contact with your face creates a better seal, choose a mask with the widest skirt you can find.
Wash and dry your hands. Apply about an inch of non-gel toothpaste to the dry mask lens. Smear the toothpaste all over the inside and outside surfaces of the lens. Use a soft, clean washcloth to scrub the lens with gentle circular motions. Rinse thoroughly with cool, clear water. Pat the mask dry with a soft, clean towel. Repeat five to seven times. This pretreatment removes the coat of silicone that accumulates on new masks during manufacturing. The silicone is remarkably resistant to defogging methods.
Apply one drop of commercial defogger to the inside of the dry mask lens just before you enter the water. Use clean fingers to spread the product and coat the entire lens surface. Give it a quick rinse-off with salt or fresh water. Don’t touch the lens after you rinse it.
Spit inside your dry mask if you don’t have defogger. Coat all surfaces of the lens evenly with clean fingers. Rinse briefly with salt or fresh water. Don’t touch the lens with your fingers afterward.
Dry your face with a towel just before pulling the mask on to avoid adding moisture to the inside lens surface. Because your warm breath encourages fogging, practice not exhaling through your nose while you’re wearing the mask. The idea is to allow minimal moisture to enter the mask.
Avoid removing the mask from your face once you have it securely in position. Anytime you take the mask off, warm, moist air quickly comes into contact with the cold inside surface of the lens. This causes moisture to condense on it, resulting in fog.
Rinse your mask with clear lukewarm or cool water after every use. Pat it dry with a soft, clean towel. Wash it with mild soap periodically to prevent dirt buildup that can cause fogging. Rinse the mask thoroughly and pat dry. Dirt and oils give moisture droplets something to hang onto -- the lens surface. Washing also extends the life of the mask.