The largest and oldest iceberg in the world, named A23a, is on the move again after being stuck in a votex for months near the South Orkney Islands. It is now drifting in the Southern Ocean.

A fter more than three decades of being stuck in theWeddell Sea, the world’s largest iceberg, A23a, has broken free and is now drifting northward.This trillion-tonne iceberg, which weighs almost ...