I have spent many months on research vessels in the waters around Antarctica. For much of that time I was surrounded by ice: blue ice, green ice, brown ice, yellow ice, blindingly white ice, even pink ice. Some of the ice was flat, some formed ramparts, much lurked in the ocean with most of it invisible. 

Ice can be a visual treat, provided you are on a suitably sized and carefully piloted icebreaker. It provides texture in an ocean environment that might otherwise be featureless, it damps down the ocean swell and it provides unlimited photographic opportunities for those fortunate enough to venture to the far south. 

Polar ice comes in two basic varieties: salty and fresh. Around the continent the ocean freezes in autumn to form a fringe of sea ice that is thin (less than two metres) and fairly salty. This is the pack ice zone and it can effectively double the area of the continent each winter. It then shrinks back in summer to coastal areas. On this floating platform live the seals and penguins that are the living icons of the Antarctic, and the seasonal formation and melting of the ice powers the productivity of the ocean that feeds them all. 

The second type of ice originates on the continent itself and this is where icebergs come from. Snow falling on cold, dry Antarctica over millennia slowly compacts and forms ice, often several kilometres thick, and this ice sheet slowly flows down from the continent’s interior to the coast in vast ice streams and glaciers. 

This ice is formed from the pure snow that falls and consequently it is about as fresh as it is possible to be without distillation. When these vast rivers of ice reach the coast, they continue to flow, forming extensive floating ice shelves or ice tongues extending out into the ocean. Eventually, the wind and waves break up these icy intrusions and icebergs are formed. The bergs drift with the currents. Some become stranded in shallow waters, others head north into warmer waters where their dissolution is accelerated. 

The city-sized, flat-topped, tabular bergs of the Antarctic are formed when rifts cause significant portions of the vast ice sheet to calve. Smaller, more jagged bergs are formed when glaciers disgorge into the coastal waters or through the disintegration of the larger bergs.

Sighting an iceberg in temperate waters is a rarity that attracts attention and grabs newspaper headlines. Similarly, on any voyage into the Southern Ocean, the first iceberg is eagerly awaited, and bets are laid on where and when it will be seen. When it is finally spotted, it becomes the subject of an inordinate amount of photographic attention, no matter how glacially nondescript it might be. 

Further south, there is never a shortage of icebergs, and as you venture within the Antarctic Circle, you become more discriminating in the icebergs that you devote your photographic attention to.

Your camera never stays still for long, however. In the land of frozen water, there is an infinite assortment of forms that ice can take. The tremendous variety of shapes, sizes and colours of icebergs that keeps Antarctic photographers active arises from the actions of the wind, the waves and even the wildlife. 

Then the ever-changing summer light of the region, with its endless sunsets that merge into sunrises, can transform even the most mundane berg into a citadel of blazing colour.

My computer hard disc bulges with hundreds of shots of the sun slowly setting over fields of icebergs, each one beautiful and unique. 

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Perhaps the most prized sightings, because of their rarity, are the jade bergs. 

Jade bergs are not found throughout the Southern Ocean, and until 2006 I had only rarely seen them, and never close enough to capture adequately on film. These icebergs can vary in colour from emerald-green to iridescent blue, and can be solid, looming monoliths or striated sculptures with vivid irregular strips of pure translucent beauty. 

When you see a blue-striped berg with the light streaming through it, you know you have seen one of the true wonders of the Antarctic. 

There are two basic reasons why icebergs can be so vividly coloured. The deepest jade is formed when frigid seawater is driven deep below the ice shelves in the great Antarctic embayments by the ocean circulation. The freezing point of seawater decreases with depth, and the seawater, which is at the surface freezing point of -1.9ºC, is above the local freezing point when it comes in contact with the ice at deeper than 1,000 metres. This “warm” salty water melts the ice, but this addition of fresh water decreases the water density, and it rises as a buoyant plume along the underside of the floating ice shelf, until it eventually reaches a depth where it is at the local freezing point again. 

Ice crystals form in the water and float upward, scavenging organic material in the sea water, and these crystals refreeze onto the base of the ice shelf, forming a layer of organic-rich marine ice. When the ice shelf fractures into icebergs, some of these have a layer of green marine ice, and as they travel north, waves and wind sculpt them, and when they roll over the jade layer can appear above the surface. 

Unlike ice formed from snow, the jade ice is largely bubble-free and hence is highly transparent. The darker colour also makes them melt faster in the summer sun, leading to further erosion and layering.

Some blue icebergs are formed rather differently. High on the ice sheet there are expanses of near-transparent ice, most formed from eons of melting and re-freezing of compacted snow. Blue ice is diamond-hard and uncannily transparent because of the lack of impurities, and is often quite distinct from the white ice that surrounds it. Like all Antarctic ice, it is fated to end its life in the ocean and the sculpting forces of wind and waves take over to carve a transient beauty that is rarely seen.

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Photography from an ocean-going research vessel can be challenging. Not only does the ship move constantly and vibrate like a jack hammer, it is also on a fixed schedule and generally on pre-determined transects. The ship cannot change track or speed, so many first-class photographic possibilities are frustratingly lost as tantalising dots disappear into the background. 

However, big scientific surveys in the waters surrounding Antarctica can cover vast areas, so they offer the possibility of visiting large swathes of the ocean and a variety of different environments. Although my research focussed on the animals and ecology of the Southern Ocean, my most striking photographs were taken of the Antarctic’s icescapes rather than of its animate inhabitants. 

Stephen Nicol was born in Ireland, completed a BSc in zoology in Scotland, an MSc in oceanography in England, a PhD in biology in Nova Scotia and an MA in creative writing in Tasmania. He worked at the Australian Antarctic Division as a research scientist and program leader from 1987 to 2011. He was awarded the Australian Antarctic Medal in 2011 for services to Antarctic research and management.