Something remarkable has happened to A23a, the world’s biggest iceberg.

For months now it has been spinning on the spot just north of Antarctica when really it should be racing along with Earth’s most powerful ocean current.

Scientists say the frozen block, which is more than twice the size of Greater London, has been captured on top of a huge rotating cylinder of water.

It’s a phenomenon oceanographers call a Taylor Column - and it’s possible A23a might not escape its jailer for years.