A diving mask is an item of diving equipment that allows underwater divers, including scuba divers, free-divers, and snorkelers, to see clearly underwater. Surface supplied divers usually use a full face mask or diving helmet, but in some systems the half mask may be used. When the human eye is in direct contact with water as opposed to air, its normal environment, light entering the eye is refracted by a different angle and the eye is unable to focus the light on the retina. By providing an air space in front of the eyes, the eye is able to focus nearly normally. The shape of the air space in the mask slightly affects the ability to focus. Corrective lenses can be fitted to the inside surface of the viewport or contact lenses may be worn inside the mask to allow normal vision for people with focusing defects.
Snorkeler wearing a clear silicone diving mask
Views through a flat mask, above and below water
Disassembled components of a single-window, low-volume dive mask
Assembled diving half-mask showing the retaining strap
Diving equipment, or underwater diving equipment, is equipment used by underwater divers to make diving activities possible, easier, safer and/or more comfortable. This may be equipment primarily intended for this purpose, or equipment intended for other purposes which is found to be suitable for diving use.
Surface supplied commercial diving equipment on display at a trade show
A US Navy diver at work. The umbilical supplying air from the surface is clearly visible
Diver in standard diving dress entering the water at Stoney Cove, England
Scuba diver with single cylinder and open circuit regulator