It’s a floating mass of pure white ice, about the size of Greater London.
And now the world’s largest iceberg, called A23a, has completed a pirouette during its journey towards the Southern Ocean.
NASA satellite imagery shows the tooth-shaped berg spinning more than 360-degrees between December and February just north of the Antarctic Peninsula.
A23a is gradually being eroded by waves and melting due to warmer waters as it moves northwards, after 30 years of being grounded to the ocean floor.
According to the British Antarctic Survey (BAS), which visited A23a in December, the iceberg is travelling north at a rate of about 30 miles per day.
The world’s largest iceberg, called A23a, has completed a pirouette during its journey towards the Southern Ocean
Scientists revealed in November that the berg is on the move again. This map shows the berg’s position highlighted in blue starting in August (bottom) and in the last few weeks (top)
Carried by winds and ocean currents, it is being swept along ‘iceberg alley’ – a common route for icebergs to float toward the sub-Antarctic island of South Georgia.
‘The #A23a megaberg is in its spinning era,’ said the British Antarctic Survey, which posted the animation on X (formerly Twitter).
‘These dance moves down #IcebergAlley are part of the iceberg’s long, melty journey into warmer waters.
‘Don’t be deceived by your screen size – this is the biggest iceberg in the world, around the size of Cornwall or Rhode Island!’
EYOS Expeditions, which arrived at A23a in January, deployed a drone to take the latest snaps from the air.
EYOS videographer Richard Sidey, said A23a is ‘mind-bogglingly big’ and ‘stretches as far as you can see in both directions’.
‘I actually don’t think we can fathom just how big it is; we can only know how big it is from science,’ he said.
A23a is the surviving largest fragment of an iceberg that broke free of the Antarctic’s Filchner Ice Shelf in August 1986.
EYOS videographer Richard Sidey, said A23a is ‘mind-bogglingly big’ and ‘stretches as far as you can see in both directions’
This shot highlights the loss of a chunk of the iceberg’s mass. It’s four times the size of Greater London but getting smaller
EYOS Expeditions, which arrived at A23a in January, deployed a drone to take the latest snaps from the air
It had only moved a couple of hundred miles when it became stuck, or ‘grounded’ to the ocean floor – and ended up becoming stationary for the next 30 years.
Icebergs ‘ground’ on the ocean floor when their keel (the bit below the water’s surface) is deeper than the water’s depth.
Scientists revealed in November that the berg is on the move again, being carried northwards by wind and ocean currents.
They estimated that it has a surface area of 1,500 square miles, a volume of 263 cubic miles and a mass just below one trillion tonnes.
That makes it not only four times as big as Greater London, but a whopping 100 million times as heavy as the Eiffel Tower in Paris.
However, parts of the berg are breaking off as it gets further north, due to erosion and melting from the warmer waters.
Much like coastal erosion of land, the waves are crashing against the berg to make the gaps that grow steadily bigger until the top collapses.
This leaves little ‘stacks’ which then form smaller ‘stumps’ before melting away completely.
While A23a originally calved from the Filchner Ice Shelf back in 1986, it remained grounded on the seabed until last month
To give a sense of scale, this image shows the area of the iceberg overlaid on a map of Greater London
This is one melting process through which A23a will eventually be lost for good, but due to its vast size this may take a while.
If not sufficiently melted by the time it reaches South Georgia – the island in the south Atlantic – it could cause problems.
There’s a chance the huge berg could disrupt the feeding routines of wildlife such as penguins – for example, if it parked in an area where foraging usually happens.
‘It depends on its trajectory, but there is potential for impact to wildlife if it approaches any of the sub-Antarctic islands,’ a BAS spokesperson told MailOnline.
A23a is currently the largest iceberg in the world, but this title won’t last forever because all icebergs eventually fragment.
The former record holder was A76, which detached from an ice shelf in the Weddell Sea in May 2021, but it has since fragmented into three pieces.
