Flock and awe: Incredible moment birds fly to safety after huge piece of glacier falls into the sea missing them by inches
Mr Cornforth, 40, was in the sound with his father in a 12-foot inflatable when he first spotted the tonnes of ice falling.
Mr Cornforth, from Seattle, said: 'The sound was thunderous as the ice fell into the water.
'Since sound travels slowly in this area, I saw the birds erupt in flight before I even saw the ice falling. The last thing that I heard was the actual sound a moment later.