This is a close up of the ice cave at the face. It was hard to judge the size but there were a flock of seagulls flying in and out which gave us reference. The tower of ice to the left is about 250 to 300 feet tall. We are in about 200 feet of water now which is shallow inside of Tracy Arm. In case your tempted to enter one of these cave with your boat, we observed a part of the ceiling calve off and hit the water which sounded like a canon going off. These are very active glaciers and calve a lot. Calving is the term used for glaciers when a chunk of ice fractures off. Some times its a small piece and in rare occasions a major section will liberate itself. When a large chunk comes off it throws a hell of a pressure wave so keep your distance.