In an effort to stem the pollutions of the area - water, air and noise - only two cruise ships per day are allowed into Glacier Bay. In all honestly that's still probably two too many, but I was happy to have ours sidle up to the edge of the "safe" distance limit (a quarter of a mile, just under a half kilometer) from the aqua wall of ice for an hour or so while everyone crowded onto one side of the ship to "ooh!" and "ahh!" as portions of ice large and small would calve away from the face with a sharp, thunderous crack and fall into the water.
As you watch the wall you'll hear the sound of small cracks, sort of like the distant crack of a rifle, and often see smaller pieces falling. Many times this is the foreshadowing of a larger calving with the smaller noises followed by the larger boom and cascade of ice.
As light travels far faster than sound it's often a matter of luck to catch a dramatic chunk the size of a bus breaking away and falling, but I was glad I could catch some reasonably good pictures during the time I stood there and watched.