Many icebergs are vulnerable to capsizing. In doing so the gravitational potential energy of the ice is increased, while that of the displaced sea water is decreased. Applying the principle of the conservation of energy shows that by capsizing, there is also a net transfer of energy to the surrounding sea water. This will be a maximum for a particular iceberg geometry. For many iceberg geometries the energy transfer can be measured on the scale of nuclear explosives. Three teaching opportunities suggested by the analysis are outlined.