Icebergs are a large piece of ice which has broken off of an ice shelf or glacier, and then gone into the ocean. These pieces of ice are all fresh water ice, and can be quite massive. Some of them have been known to weigh more than half a million tonnes. You can actually watch these being created on some holiday tours around the Antarctic, from Canada to Greenland. When they fall off the ice shelf, they can create massive waves, so you need to make sure that you are in a large boat. Icebergs are a natural phenomena, but they are growing in number as the glaciers move toward the ocean faster then before, due to the changes we’ve made to our environment; global warming.Still, it makes for an amazing spectacle, one which if you ever get the opportunity to experience you shouldn’t pass up.