What are the risks involved with ice diving?

Ice diving is risky because the diver is not only underwater, but under the ice in such a position that the diver cannot surface quickly in an emergency.  This means that extra precautions must be taken.  The water is also very cold, which means that the diver could suffer hypothermia if not dressed properly and a diver's air tanks and or regulator could freeze.  Divers must be able to handle these types of submerged emergencies.  Another risk is that the diving party is on the ice surface and the ice must be able to bear the weight of the entire diving party.