An iceberg (berg is the German word for mountain) is a large piece of ice that has broken off from a glacier or ice shelf and is floating in open water.
An iceberg off Antarctica
Since the density of pure water ice is ca. 920 kg/m3, and that of seawater ca. 1025 kg/m3, typically, around 90% of the volume of an iceberg is under water, and that portion's shape can be difficult to surmise from looking at what is visible above the surface. This has led to the expression "tip of the iceberg", generally applied to a problem or difficulty, meaning that the problem is only a small manifestation of a larger trouble.
An iceberg near Newfoundland
The mass can be very durable and can easily damage sheet metal. As a result of these factors, icebergs are considered extremely dangerous hazards to shipping. The most famous sinking from an iceberg collision was the destruction of the RMS Titanic on April 14, 1912.
The first to explain the formation of icebergs was the Russian peasant prodigy Mikhailo Lomonosov. In the 20th century, several scientific bodies were established to study and monitor the icebergs. The International Ice Patrol monitors the presence of icebergs in the northern Atlantic Ocean and reports their movements for safety purposes.
Iceberg - photomontage
of what a whole iceberg might look like
The Antarctic icebergs are monitored by the National Ice Center and are named. The NIC assigns each iceberg larger than 10 miles along at least one axis a name composed of a letter indicating its point of origin and a running number. The letters used are as follows:
Iceberg B15, which calved from the Ross Ice Shelf in 2000 and initially had an area of 11 000 km², was the largest iceberg ever recorded. It broke into two in November 2002. As of December 2004, the largest remaining piece of it, iceberg B15A, with an area of 3000 km², is still the largest iceberg (moreover, the largest floating object) on Earth.
- Iceberg gallery (http://www.ecoscope.com/iceberg/index.htm)
Iceberg is also a fashion label and a lettuce variety.