Wiktionary
n. A mask worn by divers underwater over the eyes or face to allow them to see clearly underwater, having a watertight seal around its edges to hold it securely to the face.
Wikipedia
A diving mask (also half mask, dive mask or scuba 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. By providing an air space in front of the eyes, light enters normally and the eye is able to focus correctly.
Usage examples of "diving mask".
The kid was trailing him by about twelve feet, features barely visible in the full-face diving mask.
Taking several deep breaths, he pulled his diving mask over his face, making certain it was snug and the collecting fins were clear.
Immediately her eyes widened behind the tinted diving mask as she saw the wedding ring on her finger.
He felt it like a pressure on his face, like a diving mask being shoved into his cheeks and forehead by the overwhelming pressure.
The heaving seascape was no help at all, but she found she could see a good deal by donning her diving mask, immersing her head, and peering down through the water.