Mega-iceberg A23a, formerly the world's largest, turns into bright 'blue mush' as it finally dies after 40 years at sea

Satellite photo of an iceberg covered with vibrant blue stripes in the middle of the ocean.

The world's formerly largest iceberg, A23a, has been transformed into a beautiful blob of stripy "blue mush," signaling its imminent demise, new satellite photos reveal. The dying ice mass, which until recently was three times larger than New York City, is one of the oldest bergs on record, now nearing its 40th birthday.

A23a is an oddity among icebergs. The megaberg, dubbed the "queen of icebergs," broke off from Antarctica's Filchner-Ronne Ice Sheet in the summer of 1986, but quickly became stuck in place when its submerged bottom caught on the seafloor. It remained trapped for most of the last four decades, barely shrinking in size due to its close proximity to its parent ice shelf. However, A23a finally broke free from its seafloor tether in 2020 and began drifting away from Antarctica.