Dive Mask

A mask enclosing the eyes and nose that creates an air space so a diver can see clearly and equalize the mask as pressure increases.

A dive mask gives your eyes the air space they need to focus underwater. Without one, everything is a blur because light bends differently entering the eye from water. The mask encloses the nose as well, and that is not a comfort feature: you must be able to exhale into the mask through your nose to equalize its air space as pressure rises, otherwise you get the bruising known as mask squeeze.

The refraction of light through the flat lens and the air gap makes objects appear about 25 percent larger and closer than they really are, something new divers notice when a distant turtle turns out to be farther away than expected. A low volume mask is easier to clear and equalize, and tempered glass lenses are standard for safety.

Fit is everything: press the mask gently to your face without the strap and inhale through your nose, and a good mask stays put. Defog before every dive, and practice mask clearing until flooding it is a non-event, because a leaky mask is one of the most common sources of new diver stress.