Iceberg n. : A large mass of ice, generally floating in the ocean.

Example:
What would happen if a part of an Iceberg were suddenly removed?

Taxonomy
iceberg, ice, shape, the International, tabular icebergs, free encyclopedia, the icebergs, longitude, the Ross, portion, monitor, 03-25, tip of the iceberg, icebergs of Newfoundland, Iceberg B-15, glacial ice, Antarctic Icebergs, Iceberg B15.

Defination from the web:
Iceberg calved from the Ross Ice Shelf. Because the density of pure ice is about 920 kg/m³, and that of sea water about 1025 kg/m³, ... This has led to the expression "tip of the iceberg", generally applied to a larger problem or difficulty, meaning that the visible trouble is ...