Why Do Divers Spit In Their Masks?

Why Do Divers Spit In Their Masks?

There is only one reason divers spit in their masks, to stop them fogging! Your saliva acts as a surfactant; it smooths out the microscopic imperfections on the inside of the mask lens. This stops the moisture inside the mask from forming condensation, just like it does on your bathroom mirror. Bingo…no mask fog!

There is nothing more annoying than being on a dive and your mask keeps fogging up! Not only can this throw you off your perfect buoyancy, but you also can’t see all the beautiful marine life (or your buddy)!

Of course, you can clear your mask underwater. But this can become frustrating if you keep having to do this while increasing your air consumption. 

In this article, we will talk about: 

  • Why does spit work so well?
  • Why spit? 
  • Are there other methods?

Why does spit work so well?

Spit smooths out the inside surface of the mask, preventing moisture from building up!

It is crazy to think, that something produced in our mouths, works so perfectly as an anti-fogging agent for our masks. But how does it work? To understand this, we need to dive into more detail. (Yes, I made a diving dad joke again.)

On the inside of our diving masks are tiny microscopic bumps, making the surface rough. When the water on the outside of the mask is colder than the air inside, the moisture in our masks condenses on the rough surface of the mask lens.

This causes the mask to fog, just like your bathroom mirror. (Annoying!) 

So why would spitting prevent this? Surely our saliva can’t be so useful? To put it simply, by spreading our spit around the inside of the mask, we are smoothing the surface and preventing condensation from building up. 

This is why it is important to only rinse your mask after spitting in it, so the spit remains on the lens. If you wash the mask, you remove the spit and all its benefits. 

A clear mask is a happy mask!!

Why spit? 

Spit is great. We have an unlimited supply, it does not damage the ocean and it is free! 

You do not have to worry about forgetting your anti-fog because it is located in your mouth. 

Another reason why divers love to spit in their masks is that it is reef safe. Our spit does not damage the corals or upset the ecosystem. 

Spitting in diving masks is also convenient. You don’t have to carry around bottles of shampoo or antifog spray on the boat, in your BCD or wetsuit pockets! 

Are there other methods? 

Other methods include shampoo, toothpaste and anti-fog sprays. 

Defogging masks can be a pain. Divers spit in their masks before every dive, but there are diving mask rituals to do before getting to this point. 

After buying a brand new mask, you would assume you can just take it straight into the water. But this is not always the case.

The first thing to do to your mask to prevent fogging is to burn it. I’m sure you’re thinking “What? I just bought it!”. I know it sounds crazy, but this method is great. Using a lighter, burn the inside of the mask lens, to remove the silicone layer. 

Be careful to not burn the silicone, just move the tip of the flame along the inside of the glass. 

After burning your mask, another great thing to do is to rub toothpaste on the inside of the lens, then let it sit overnight. Make sure you wash it all off the next morning, as you do not want toothpaste in your eyes! 

These two methods are very reliable and have always done their job. If for some reason this is not working for you, you can purchase an anti-fogging mask spray. However, if you choose this method, please make sure it is reef safe! 

We want to protect our beautiful oceans, not destroy them with our chemicals. 

Burning your mask and rubbing toothpaste inside is a must for most new diving masks. Once you have done these methods once or twice, your mask should be good to go!

Don’t Forget Your Dive Insurance!

Before you go out on any dive trip or holiday, it is essential to make sure you have insurance that covers you if something goes wrong. Check out our dive insurance article for more information.

Or go straight to these dive insurance company websites:


Diver Alert Network (DAN)

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Final Thoughts

So you now know the reason behind divers spitting in their masks! Next time you see someone rubbing and rinsing off their spit, you will know why! Spit is the favourite method as it is convenient, reef-safe and free. 

Spitting in your mask before every single dive is a great way to prevent it from fogging.

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Bethany Nyquist

Bethany is a writer, an Environmental Scientist and Dive Master, exploring the underwater world. Practising Underwater Photography, Bethany aims to raise awareness for and help protect marine life.

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