Scientists are monitoring an iceberg - one of the largest now in existence - that has broken off from an Antarctic glacier and is heading into the open ocean.
The iceberg covers about 660 square kilometres - roughly the area of Lake Taupo - and is up to 500 metres thick.
NASA glaciologist Kelly Brunt said the iceberg known as B31 separated from Antarctica's Pine Island Glacier last November.
"It's one that's large enough that it warrants monitoring," she told Reuters, noting that US government organizations including the National Ice Center keep an eye on dozens of icebergs at any given time.
The iceberg's present location is not in an area heavily navigated by ships.
Scientists are especially interested in this iceberg not only because of its size but because it originated in an unexpected location.
The glacial crack that created the iceberg was first detected in 2011, Dr Brunt said.
Pine Island Glacier has been closely studied over the past two decades because it has been thinning and draining rapidly and may be an important contributor to sea level rise.
Scientists say the iceberg has floated across Pine Island Bay, a basin of the Amundsen Sea, and is likely to be swept up soon in the swift currents of the Southern Ocean.