Icebergs melt as they are moving around the ocean. This makes them unstable. They could turtle. Meaning that it could flip over. Others could split apart or break off into smaller pieces.
Some icebergs are very large.
There is one iceberg that broke off last March that scientists are tracking. At one point it was as big as the state of Connecticut. Scientist plan on placing equipment on the iceberg so that can track its movements. Here at Palmer we cannot get any closer than 3 times the height of the iceberg. It is a good rule because the water temperature is so cold you would only survive a few minutes in the freezing water.