When the human eye is in direct contact with water, light entering the eye is refracted by a different angle and the eye is unable to focus light. It needs air space in front of the eyes so that light can enter normally and the eye can focus correctly. This is the primary purpose of the dive mask. Dive masks are usually made of durable tempered glass with a watertight rubber or silicone seal around the diver’s face. A strap keeps a dive mask in position.

The most important thing to consider when choosing your dive mask is that it is properly sealed to avoid leaks. They come in a variety of designs and since there are also different face shapes, you will probably spend some time trying on several designs to get the perfect fit. You will also have to decide between a single and a dual pane glass port. Singles give an unencumbered view while a dual pane allows the ports to come closer to the eyes. This improves left to right vision considerably.