 A diver in a pool wearing an AGA full face mask A diver wearing an Ocean Reef full face mask A full-face diving mask is a type of diving mask worn by SCUBA divers so that they can talk with the surface or other divers.
The diver can speak and hear inside the mask. This allows communications equipment to be installed in the mask and is very useful for working divers.
Some fullface masks have a mouthpiece inside: with those, if the mask floods, the diver can breathe again before clearing the mask; but the mouthpiece is strapped in like a gag, making his speech very distorted.
Without a mouthpiece inside the mask, the diver can talk fairly clearly, but if the mask floods, he cannot breathe until the mask is cleared. There also is the problem of "dead space" inside the mask causing risk of carbon dioxide buildup.
There also is the problem of the inside of the mask window misting. Some Russian gasmasks are designed so that when the wearer breathes in, the inflow of air blows over the inside of the mask window and tends to evaporate any mist deposit on it.
Many industrial breathing sets and most gasmasks for use on land have full-face masks.
See this link and this link for examples.
| 
