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Why your goggles get foggy and how to fix them

We’ve got the answer to why swimming goggles fog up and community-sourced tips for preventing your goggles from fogging up next time you swim.

There’s nothing more frustrating than having foggy goggles.

Fogged-up lenses disrupt your rhythm and flow and restrict your vision, and it’s super annoying.

Whether you’re training, enjoying a leisurely swim or in the middle of a race there is no good time for foggy goggles.

To get to the bottom of this swimmer’s lament, we have researched the causes of foggy goggles and taken advice from the swimming community to find the best remedies to prevent your goggles from fogging.

Why do your goggles fog up?

There are multiple different reasons why your goggles might fog up but the science behind the main reason why your goggles are fogging up is surprisingly simple.

It all comes down to the temperature difference on either side of the goggle lenses; the side that sits on your face and the side that’s in the water.

Research has found that when the air inside your goggles is warmer than your goggle lenses, warm air molecules hit the cooler lenses and condense into water molecules which then causes your goggles to fog.

It is the same reason why people who wear glasses experience their lenses fog up when they open the oven or leave an air-conditioned building out into the warmer outside air.

While you might not feel it, when you swim your body can heat up quickly regardless of the water temperature, which can create a temperature imbalance, causing your goggles to fog.

Apart from this scientific answer, there can also be issues deriving from the anti-fog treatment many goggles have applied. These include:

  • The anti-fog treatment becomes less effective over time from wear and tear
  • The anti-fog treatment has completely come off the inside of the lenses.
  • Too much moisture has been produced within the lenses and the anti-fog treatment can’t handle it.
  • A swimmer using anti-fog spray before their swim to help prevent foggy goggles

    How to prevent your goggles from fogging

    Almost all goggles these days are sold as ‘anti-fog’ but that doesn’t necessarily mean that they will never fog for their lifetime.

    What the ‘anti-fog’ means is that the inside of the goggle lens has been treated with a silicone-type film that helps repel water from the lens causing it to run off rather than form a mist/fog.

    Over time, this anti-fog treatment is broken down, usually by repeatedly wiping with your finger. For ocean swimmers, this is compounded by the presence of tiny sand granules in the water which act like sandpaper on the lens.

    If you’re finding your goggles are starting to fog up, either due to foggy-goggle-science, or you’ve simply worn out the anti-fog, there are several tried and tested solutions – as reported by ocean swimmers – that you can try to minimise the fog.

  • Put your goggles on while they are dry. This can help minimise the excess moisture between your skin and the inside of the goggle lens.
  • Anti-fog spray. Most of the anti-fog sprays on the market contain a hydro-phobic solution which helps to repel water from the goggle lens, helping it to run off rather than form a fog.
  • Baby shampoo. Yes, you heard it right. Gently rub the baby shampoo onto the inside of the goggle lens and leave it to dry for 10 minutes before rinsing them out. This helps to create a barrier that will help repel the fog. You can use any kind of shampoo but baby shampoo tends to be much nicer on the eyes.
  • Store your goggles in a case in a cool place. By storing your goggles in a case in between swims – out of the heat/sun – you help to preserve and protect the anti-fog film that lines your goggle lens.
  • Dishwashing liquid. You can put a thin layer of dishwashing liquid into the inside of your goggles lens and let sit for 10 minutes before washing it out gently and letting it dry.
  • Spit in your goggles. While it might be unsavoury, many swimmers swear by it. It’s also the most convenient as you’ll have this option with you at all times.
  • Coat the lenses in toothpaste. Another odd one but some swimmers we’ve spoken to keep a tube in their gear bag for just this reason.
    • Written by Suzie Ryan on 20 February 2024
    • (Updated on 20 February 2024)



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