Real science: Just how big can an iceberg be?

I've never been close to glaciers or icebergs, so I got a shocker when looking at a recent Nature report: "Giant iceberg cut adrift Antarctica’s Pine Island Glacier shed a massive iceberg last week..., breaking along a deep rift that researchers had been monitoring since 2011. The ‘calving’ event dumped a 720-square-kilometre chunk of ice into the Amundsen Sea off western Antarctica, the German Aerospace Center (DLR) reported on 9 July, on the basis of images collected by its TerraSAR-X satellite."

720 square kilometers!! By comparison, Mumbai is just 67.7 (City) + 369 (Suburban) = 436.7 sq km. This monster iceberg is the 65% bigger than the city!