How to Stop Your Scuba Mask Fogging up

It’s happened to everyone, I am sure!  The dratted fogging up of a mask during a dive – whether it be once or twice – or continuously, it is such a pain.  So why does it happen and what can you do to prevent the fogging problem?


Where the fog is from:

Simply put, it’s condensation.  Water vapour in humid air inside your mask cools and condenses as it comes into contact with the colder glass on the inside of your mask (cooled by water on the outside of the mask). The surface tension of the glass inside your mask promotes the formation of condensation and fogging.  To stop this from happening, you need to treat the inside of the glass with something that will reduce the surface tension of the glass, so that there is nothing for the moisture to “stick” to.

Usually, this surface tension is caused by silicone oils left over during the manufacture of a new mask, or from suncream or oil on your fingers.


Step 1:  How to prepare your new dive mask before diving

We recommend rubbing white (not gel) toothpaste inside and out (on both the skirt and glass) of a dry mask with your finger; a soft brush or cloth.  Rinse completely with fresh water.  Rinse and repeat about 3 – 4 times. We do not recommend that you “burn” the glass of your mask with a flame.  This can easily damage your mask.  Mind you, we do have lots of great masks for sale in our dive shop if you need to replace your now melted new mask….

Step 2:  Pre-Dive treatments to stop your mask from fogging

Regardless of which of the following pre-dive treatments you choose, remember to apply evenly to a dry mask with oil and suncream-free fingers. The treatment will not stick to oil or wet glass.  This is why certain spots on the inside of your mask still fog up, even after treating your mask… and no matter how many times you clear your mask during that dive, the fog just keeps on coming back…


Commercial products:

There are a number of commercial products available, including those for sale in our dive shop.  Very easy to use, one treatment should last for a couple of dives and a bottle will last you a long time. All you need to do is rub a small dot of liquid evenly over the inside glass of your dry and oil-free mask.  Rinse with either fresh or sea water before diving and take care not to touch the glass on the inside of your mask during or after rinsing.


Baby Shampoo:

Inexpensive, baby shampoo also comes in small containers suitable for bringing on the boat and for travelling with.  It’s also biodegradable and does not hurt your eyes.  Apply as above for the commercial products.  Just be careful not to spill the soapy water onto the deck of the boat when rinsing your mask as this will cause a very slippery deck and a very unhappy skipper!



Spit is usually readily available and it’s free but it isn’t as long-lasting as the commercially bought products. Application is also as above – spit onto the dry glass of your mask with oil-free fingers, rub around evenly and rinse.  Over time, the use of spit can cause a green/black mould to grow between the glass and skirt of your mask.  This is apparently harmless but does not look very attractive if you have a clear skirt.  Please note that when on a larger dive charter boat or a liveaboard, do not rinse an already spat-into mask in the rinse tank as this is a sure way of spreading germs.

A number of years ago, one of our students was a gorgeous model who had won a scuba diving course in a competition.  When we were getting ready for our first pool session, she took her mask and asked:  “What do you call that stuff you put inside your mask to stop it from fogging up?”  Deon and I replied at exactly the same time “Spit!”  we laughed.  Needless to say, she took to spitting in her mask quite readily.  Who said scuba diving was glamorous?!!