A23a: Tracking the world's biggest iceberg as it drifts towards oblivion

A23a: Tracking the world's biggest iceberg as it drifts towards oblivion The world's biggest iceberg - more than twice the size of Greater London - is on the move. After a few weeks loitering on the fringes of Antarctica, it’s begun to drift at pace once more. The world's biggest iceberg - more than twice the size of Greater London - is on the move. After a few weeks loitering on the fringes of Antarctica, it’s begun to drift at pace once more. The world's biggest iceberg - more than twice the size of Greater London - is on the move. After a few weeks loitering on the fringes of Antarctica, it’s begun to drift at pace once more.

A23a, as it’s known, broke away from the Antarctic coastline way back in 1986, but it's only recently begun a big migration. For more than 30 years, it was stuck rigidly in the bottom-muds of the Weddell Sea like a static "ice island". A 350m-deep keel had anchored it in place. It took gradual melting until 2020 to allow the berg to re-float and start moving again, slowly at first, before currents and winds then swept it north towards warmer air and waters.

Today, the behemoth is drifting along the 60th Parallel, close to the South Orkney Islands, about 700km (430 miles) northeast of the tip of the Antarctic Peninsula.