Why Dive Masks And Swim Goggles Are Needed:
Light behaves differently in water than in air, distorting what you see. Particularly when you are swimming or diving, objects appear larger and closer than they actually are. This can hamper your hand-eye coordination.

Swim goggles and diving masks work by providing a pocket of air in front of you that enables light rays to travel to and through your eyes in a more precisely focused way. Because water refracts (bends) light differently than air, your vision will be blurred and out of focus if your eyes are in direct contact with water — even if you normally see perfectly well. In fact, in such conditions, a person who has 20/20 visual acuity on land will be legally blind underwater. If you wear prescription eyewear because you are nearsighted, are farsighted or have astigmatism, you also will need corrective lenses to see clearly underwater. But your prescription may need to be changed, because the distance between the lens of your goggles or diving mask and your eyes typically is different from the distance between your eyeglasses lenses and your eyes. (This also is one of the reasons your contact lens prescription is different from your eyeglass prescription if you have moderate or high myopia.) Hudson Valley Eye Doctor can adjust your prescription for underwater use. Your choice of a diving mask or goggles will depend on your activities and specific needs.

Wearing prescription swim goggles means you don't have to swim with blurry vision and you don't have to risk losing your contacts or getting eye infections from waterborne microorganisms. Shown here are Shark swim goggles by Liberty Sport.