We left Skagway and sailed overnight to arrive at Glacier Bay National Park early the following morning. I did catch this classic Alaskan sunset from the balcony that evening as we set sail.
We arrived in Glacier Bay the next morning and would spend the next 9 hours looking at ice cubes. Sorry, I could not resist. As you travel up the bay toward the head first you do see small ice cubes in the water. Those ice cubes are called bergies It tends to make one feel like olive in a martini on the rocks.
As you progress toward the head of the bay those bergies get larger and larger. You will see some minor glacier like things on either side of the boat. I was told most of those will melt before the of the summer season and don't justify the use of the term glacier.
You may wonder why your ship is moving as slowly as you move up the bay. Safety is the reason and it is twofold. Safety of the park and the bay is one of those. The maximum speed is dictated by the US park service and I seem to recall that a park service employee must be on board to monitor that. The second safety is your safety. Typically only about 1/9th of an iceberg is visible above the water line. But that is not an absolute value. It is always possible that the underwater mass could be larger. The closer to the head you get the larger they get.
A glacier is made from falling snow that accumulates, packs and freezes more solid as it does. Even so there is trapped air inside the ice so if you get close to a larger chunk you may hear the sound of escaping gas, air in this case. It can sound a lot like an Alka-Seltzer in a class of water. As a matter of fact the nickname is a bergie seltzer.
So where to all those floating bergies come from? The glacier starts high up on the mountain as flows in solid from to the sea picking up hairline cracks and fracture along the trail. Where it reaches the sea the salt water act a thawing agent. In the warm months big and small chunks of break off from the main body in a process called calving. This happens because you have this big hunk of ice suspended out over the sea where the salt water and warmth tend to eat away at the base of it until it breaks off.
Think of the glacier as an ice cube with a groove cut perpendicular across the cube and balanced on the rim of a glass. Sooner or later that ice cube will break at the crack. When that fractured cube hits the warmer water the trapped gases expand and it ultimately explodes into smaller pieces. As it floats out to sea this process is continually repeated with ever smaller pieces being the result.
The picture below was taken at the head of the bay. That glacier does not look all that impressive until you consider this was taken with a point and shoot camera from a mile away.
No picture or video is ever going to do this portion of the trip justice. This is something you have to see and experience firsthand to fully appreciate.
More reading and Glacier images can be found here Wikipedia article.