The world's largest iceberg is on the move for the first time in more than three decades. At almost 4,000 square kilometers, the Antarctic iceberg called A23a is roughly three times the size of New York City. | Reuters

Visible from space, the world’s largest iceberg is headed towards a remote Antarctic island, threatening local animals. A23a, the trillion-ton megaberg, which is 40 meters tall, twice as broad as London, and viewable through satellites, could either collide with the island of South Georgia, or get trapped in ocean currents revolving around it. Past iceberg collisions on the island, which is home to King penguins and about half of the world’s population of Southern elephant seals, have led to mas

Watch closely— Two men are climbing an iceberg. Suddenly, it rolls over, and they fall into the icy sea. How are icebergs formed? They're not from frozen seawater, but from ancient glaciers breaking off due to waves or climate change. Glacial ice is freshwater, which is less dense than seawater— so when it falls into the ocean, it floats upward. Only about 10% of an iceberg is visible above water— that’s the origin of the phrase “tip of the iceberg.” Collisions are dangerous. The Titanic famousl