air hole

"We know an air-hole when we see it—and I can't see any of them around here," replied Paul.

The bailiff stopped; the air-hole was tightly closed with clods of earth; and the cavern was plunged into utter darkness.

This was boarded up the next day, only a small air-hole left, of about six inches diameter.

He could wait for what he wished as the Eskimo sits for days at the air hole until the seal appears.

His friend, who was skimming along in advance of him, suddenly fell into an air-hole and sank out of sight.