Gary S asked in SportsSwimming & Diving · 1 decade ago

Why do we need a mask to see clearly underwater?

It seems natural to open your eyes underwater, why the poor results?

3 Answers

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  • 1 decade ago
    Favorite Answer

    Unfortunately the answer above is only partially correct. Those are reasons to wear goggles or mask to eliminate irritation but doesn't explain why we can see.

    The reason we can see underwater with a mask is because there is air trapped between the lens and our eyes. As mentioned, our eyes are for use in an air environment. When we try to see underwater we end up with a different focus angle due to waters refraction properties. It's the same thing as trying to focus on your finger when it's in contact with your eye.

    The lens of a mask or goggles allows the images to remain a distance away from our eyes so that we can focus on them through an air environment.

    Source(s): Registered CPO (Certified Pool Operator) with the National Swimming Pool Federation http://www.nspf.com/ and maintaining public access swimming pools for many years now.
  • 1 decade ago

    Lenses, like the ones in cameras and the one in your eye, are able to bend and focus light because the speed of light outside the lens, and the speed of light inside the lens are different. The amount the light is bent depends on the difference in the two speeds. The focusing of light by your eye depends on light moving from air into the lens, it's shaped for that. If light is coming in from water, the amount that it bends in the transitions is different, so the lens focuses differently. Goggles put an air layer in front of your eye's lens so that the focusing works correctly.

    I read an article once about contact lenses for swimming that corrected for the air/water difference so that you could see underwater without goggles. I don't think that they were ever marketed commercially.

  • Kisses
    Lv 4
    1 decade ago

    our eyes are used to seeing in a waterless environment so if you use your eyes underwater, your eyes will get irritated. plus, a mask protects your eyes from irritants that might be present in the water.

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