Iceberg

 (300 ft) above the sea surface and have mass ranging from about 100،000 tonnes up to more than 10 million tonnes. Icebergs or pieces of floating ice smaller than 5 meters above the sea surface are classified as "bergy bits"; smaller than 1 meter—"growlers".The largest known iceberg in the North Atlantic was 168 metres (551 ft) above sea level، reported by the USCG icebreaker Eastwind in 1958، making it the height of a 55-story building. These icebergs originate from the glaciers of western Greenland and may 

have interior temperatures of −15 to −20 °C (5 to −4 °F)

Oceanography and ecology

The freshwater injected into the ocean by melting icebergs can change the density of the seawater in the vicinity of the iceberg. Fresh melt water released at depth is lighter، and therefore more buoyant، than the surrounding

 seawater causing it to rise towards the surface Icebergs can also act as floating breakwaters، impacting ocean waves.

Icebergs contain variable concentrations of nutrients and minerals that are released into the ocean during melting. Iceberg-derived nutrients، particularly the iron contained in sediments، can fuel blooms of phytoplankton.Samples collected from icebergs in Antarctica، Patagonia، Greenland، Svalbard، and Iceland، however، show that iron concentrations vary significantly،complicating efforts to generalize the impacts of icebergs on marine ecosystems

Antarctica
In Antarctica many icebergs break off from the Antarctic ice cap، some of which are several times larger than those in the North Atlantic. As the maximum length of the largest reaches 320 km، and the maximum width is 97 km. These ice blocks cover an area estimated at about 13 thousand square km، and the majority of icebergs in this region are of the category of 16 km in length. In contrast، the longest iceberg measured in the North Atlantic is 4.6 km long.