Scuba masks allow you see underwater by providing an air gap between the water and the eye and various models are available from manufacturers such as ScubaPro, Mares and Cressi.
Since water has a different optical density to air, refracted light arrives in the eye at a different angle, making it impossible to focus correctly; however, providing an air gap between the eye and the water corrects this and allows us to see underwater. Modern masks are usually made from several pieces; a rigid plastic frame that holds the lens or lenses; a silicon rubber skirt to provide a comfortable and watertight seal against the face; and a silicon rubber strap.
Older designs featured a single glass lens, and indentations either side of the nose to allow the nose to be pinched for the Valsalva manoeuvre to clear the ears. However, modern masks are designed so that a silicon nosepiece protrudes forward of the lens, making it easier to pinch the nose.
A mask should be chosen for fit and comfort; to check whether any particular model correctly you should put the mask to your face without using the strap and breathe in slightly - if the mask is comfortable and does not fall away from the face it is a good fit.
One popular option is the low volume mask, which is designed so that the lens is closer to the eye, such as the Cressi “Big Eyes”, shown at the top of the page. This reduces the volume of air inside the mask; it is therefore easier to clear and reduces mask squeeze. Also, many scuba masks feature a two-lens design that can be fitted with prescription lenses if desired.
While facemasks are available with a purge valve to allow water out, they are generally only recommended for snorkelling because it the purge valve fails during a dive there is no way to clear the mask.
See the list of articles below, where we offer tips and advice as well as review different models of scuba mask.