Iceberg A23a, considered the world's largest for nearly 40 years, completely disintegrated while drifting in the Southern Ocean, the Arctic and Antarctic Research Institute (AARI) press service reported.

The iceberg calved from the Filchner Ice Shelf in 1986. At the time of its formation, it covered over 4,170 square kilometers—almost twice the area of St. Petersburg—and weighed nearly a trillion tons. After calving, A23a remained aground in the Weddell Sea for about 30 years.

It only moved in 2020 and has since traveled approximately 2,300 km north.

The iceberg later approached the coast of South Georgia Island, a British territory with a rich ecosystem.

Scientists feared it would harm local fauna, but in March 2025, A23a grounded in shallow water in a safe location.

A23a lost its status as the world's largest iceberg only in September 2025. In January 2026, its area was still approximately 1,300 square kilometers, but in the following months, the iceberg rapidly shrank, continuing to drift and break up. According to Polina Soloshchuk, chief specialist at the Arctic and Antarctic Research Institute's Ice and Hydrometeorological Information Center, over the past three months, the iceberg has traveled approximately 1,000 kilometers, crossing the boundary between the Southern and Atlantic Oceans.

Over its entire existence, A23a has lost 99% of its original area.

Currently, it does not exceed 50 square kilometers. The title of the world's largest iceberg has passed to iceberg D15A, which has an area of approximately 3,000 square kilometers.