Aialik glacier. The captain brought the boat up close, and we just sat there for about half an hour. It was awesome, in the true sense of that word. The glacier seemed alive. It crackled and snapped. Sounds like explosions went off inside it without any apparent disturbance of the surface. Every few seconds, big chunks of ice would break off the front and crash into the sea. The captain said it advanced 6 to 10 feet a day in that way.