A group of British scientists has photographed and filmed the world’s largest iceberg, A23a, after it began to move again after almost four decades stuck to the ocean floor. A23a made global headlines in late November (2023) when it moved out of the Weddell Sea sector into the Southern Ocean - the first time it had budged in 37 years.It calved from the Filchner Ice Shelf in 1986, before being grounded on the seabed nearby. A23a is now likely to be swept along by the Antarctic Circumpolar Current into ‘iceberg alley’, putting it on a common iceberg trajectory towards the sub-Antarctic island of South Georgia. Covering an expansive area of almost 4,000 sq km (1,500 sq miles), it is double the size of Greater London. A23a is not only impressive in width; its thickness is a formidable 400m (1,312 ft). To put this in perspective, Europe's tallest skyscraper, the Shard, stands at a mere 310m. Scientists aboard the RRS Sir David Attenborough reached the mega-berg at the start of December - photographing the majestic block of ice. They also collected samples of seawater around A23a. New video footage shows the enormous iceberg, stretching out into the distance beyond the research vessel. In addition to being in its awe, they hope samples from the water around the iceberg will help provide information on how icebergs drive ecosystems and their sensitivity to climate change.