Iceberg

Overview
Because the density of pure ice is about 920 kg/m³, and that of sea water about 1025 kg/m³, typically only one-ninth of the volume of an iceberg is above water. The shape of the underwater portion can be difficult to judge by looking at the portion above the surface. This has led to the expression "tip of the iceberg", for a problem or difficulty that is only a small manifestation of a larger problem.
Icebergs generally range from 1 to 75 metres (3–250 ft) above sea level and weigh 100,000 to 200 000 tons. The tallest known iceberg in the North Atlantic was 168 metres (550 ft) above sea level, reported by the USCG icebreaker East Wind in 1958, making it the height of a 55-story building. These icebergs originate from the glaciers of western Greenland, and may have an interior temperature of -15 to -20°C (5 to -4 °F).