The part of an iceberg hidden beneath the waves is seven times bigger than that above the water line

Where they occur: In the north Atlantic and off the coast of the Antarctic

Occurrences per year: 10,000 icebergs break away from the glaciers of Greenland each year

Size: Anywhere from the size of a piano to the size of a 10-storey building

Icebergs are spectacular floating masses of frozen freshwater. They are most common during the spring and summer months, as rising temperatures cause enormous lumps of ice to break away from glaciers and polar ice sheets and float out into the ocean a process known as ‘calving’.

Small icebergs that measure just a few feet across are known as ‘growlers’. Large icebergs can reach 1.6km (1 mile) in diameter and tower 60m (200ft) above the water. The part of an iceberg hidden beneath the waves is up to seven times bigger than the chunk visible on top.

Icebergs are a hazard to shipping in the north Atlantic, where on average 375 icebergs float south off the coast of Newfoundland every year. Once an iceberg breaks away into the sea, it will melt rapidly, due the effects of the seawater, but larger icebergs can travel up to 3,200km (2,000 miles) before they disappear completely.