rachelle mackintosh, Fata Morgana (SEASCAPE 2025)

A23a is the world's largest iceberg, measuring 4 times the size of New York City. It snapped off the Filchner Ice Shelf (thanks, climate change!) in 1986, but it immediately became stuck to the seafloor. Fast-forward to 2020 and it detaches and drifts off to sea ... and it's been on the go ever since, moving nearly 4,000km across the Southern Ocean towards sub-Antarctic South Georgia. It's in a super remote pocket of the ocean that's not easy to get to - but luckily our expedition ship had to change course to side-step a storm and our new route put us in its vicinity. The iceberg is so massive it took a few hours to pass its frosted escarpments. Photographed from the ship, handheld.

Images have been resized for web display, which may cause some loss of image quality. Note: Original high-resolution images are used for judging.