World’s Largest Iceberg A23a Runs Aground Near South Georgia Island

The world’s largest and oldest iceberg, A23a, has run aground near South Georgia Island in the sub-Antarctic, according to confirmation from the British Antarctic Survey (BAS).

This trillion-tonne ice giant, comparable in size to Rhode Island, began its journey when it calved from Antarctica’s Filchner Ice Shelf in 1986.

After remaining stationary in the Weddell Sea for over three decades, A23a began drifting with Southern Ocean currents in 2020, finally reaching its current position approximately 90km from South Georgia Island.

Dr. Andrew Meijers, an oceanographer with the British Antarctic Survey and co-leader of the OCEAN:ICE project, reports that the iceberg “appears to be maintaining its structure and has not yet broken up into smaller chunks, as previous ‘megabergs’ have done.” However, he predicts that “now it’s grounded, it is even more likely to break up due to the increased stresses.”

The massive berg’s journey featured an unusual scientific phenomenon in late 2024 when it became trapped in a Taylor Column – an oceanographic occurrence where rotating water above a seamount temporarily immobilized the iceberg, delaying its northward drift.

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While researchers don’t anticipate significant impacts on South Georgia’s wildlife, the berg may create challenges for commercial fishing operations. “As it breaks up over time, the smaller bergs are much harder to track,” notes Dr. Meijers. “Discussions with fishing operators suggests that past large bergs have made some regions more or less off limits for fishing operations due to the number of smaller – yet often more dangerous – bergy bits.”