Icebergs can be formed by big cliffs, which are full of ice. When the ice falls, a chunk of it stays in the water and floats, which is then an iceberg. Whenever we look at an iceberg, it looks quite small but under the water there is a huge chunk of ice underneath. As little as 10% can be seen above the water with 90% hidden below the surface. The small top just pokes out, revealing a non-menacing kind of emotion. This is why there are so many accidents like the Titanic as captains can't see the full extent of the iceberg.
In the Arctic (Northern Hemisphere), icebergs are formed from glaciers in Alaska and Greenland. In the Southern Hemisphere, icebergs start from glaciers in Antarctica. There are different types of icebergs: Bergy Bits and Growlers.