THE biggest iceberg on the planet is on the move after breaking free from the seafloor and is now heading towards a British island.

The mammoth A23a was stuck for three long decades in the middle of the Antarctic before it bizarrely started spinning on the spot.

The iceberg phenomenon is twice the size of Greater London and weighs almost a trillion tonnes thanks to it being 1,312ft thick.

It is also the oldest iceberg in the world after being created from Antarctica's Filchner Ice Shelf way back in 1986.

After it split from the Antarctic coastline it was quickly anchored to the seabed in the Weddell Sea.

Here it stayed grounded and spent 30 years sat in the middle of nowhere.

It took until 2020 for it to begin finally moving again but scientists were soon left disappointed when it stopped earlier this year.

Then they quickly noticed it was spinning around on the spot.

The remarkable movements were thanks to a natural wonder known as a Taylor Column which trapped the berg.

It causes rotating waves of water above a seamount to snatch and contain any objects in its path and hold it in place.

This unthinkable movement held on to A23a tight and only allowed it to spin around one zone for months.

It has now broken loose once again and is back on its long journey north, say experts from the British Antarctic Survey (BAS).

They confirmed that A23a has pulled away from the South Orkney Islands where it was stationed close to.

Dr Andrew Meijers, an oceanographer with the BAS said: "It's exciting to see A23a on the move again after periods of being stuck.

"We are interested to see if it will take the same route the other large icebergs that have calved off Antarctica have taken.

"And more importantly what impact this will have on the local ecosystem."

Initial predictions say the A23a will continue on the path it was on before the Taylor Column which will take it into the Southern Ocean following the Antarctic Circumpolar Current.

This is then likely to help move it towards the sub-Antarctic island of South Georgia which is actually owned by Britain.

When it enters the nearby waters it is due to begin to break down into much smaller bergs due to the warmer waters.

Experts say it will likely melt soon after reaching the island.

But it's not just the size of the ice island that's impressive.

The slab of ice is also 1,312ft thick - making it taller than the 1,016ft Shard in London.

The iceberg is being tracked by satellites and also other research teams.

Laura Taylor, a biogeochemist on board the vessel, says they hope to study the impact of the iceberg as it passes by local ecosystems.

She said: "We know that these giant icebergs can provide nutrients to the waters they pass through, creating thriving ecosystems in otherwise less productive areas.

"What we don't know is what difference particular icebergs, their scale, and their origins can make to that process.

"We took samples of ocean surface waters behind, immediately adjacent to, and ahead of the iceberg's route.

"They should help us determine what life could form around A23a and how it impacts carbon in the ocean and its balance with the atmosphere."

The previous world's biggest iceberg was the A68a - it was three times the size of London and was estimated to weigh a whopping trillion tons.

It was on a collision course with South Georgia and posed a huge threat to destroy the surrounding seafloor and ecosystem.

Luckily, it stopped around 100 miles away from the British island as it soon disappeared and completely melted away without a trace.