Howstuffworks "How Icebergs Work"

Icebergs -- giant floating chunks of ice. What else do we need to know? As it turns out, plenty. There's a lot that's deceptive about icebergs. It's true that most of an iceberg's bulk lies unseen beneath the surface of the ocean, but these seemingly sterile ice slabs also harbor their own complex ecosystems, and they shape the ecosystems that they pass through.

Alaska Image Gallery

Grant Faint/Getty Images
Iceberg off the coast of Newfoundland, Canada, near
Iceberg Alley

Icebergs can seem rather ominous -- they dot high-latitude oceans like mines, and after all, one of them sank the unsinkable Titanic. They also seem to hold a lot of promise -- could we really tow one to Los Angeles and melt it for drinking water? Could you live on one?

Scientists are still learning about icebergs. They're difficult to study. In fact, it can be hard just getting to one. While we know where icebergs come from and have a general idea how they behave, every expedition to an iceberg uncovers something new. From floating chunks no bigger than your car to massive islands of ice the size of Connecticut, icebergs come in many shapes and forms.

Go find a pair of mittens, because we're heading to the world's coldest oceans to explore on top of, inside and even underneath icebergs to find out how they work, what lives in them and why they can be so dangerous. We're even going to visit the largest iceberg ever recorded.

One other thing you should know about icebergs before we begin: They can explode.

Colorful Icebergs
Most icebergs are blue, the color of compressed glacial ice. When they've gone through a few melt/freeze cycles, icebergs turn white, the color of ice that has air bubbles trapped in it. A few rare Antarctic icebergs are a startling shade of green. These bergs formed at the bottom of thick Antarctic ice shelves, where they were in contact with seawater for centuries. The seawater froze to the ice shelf, and because it contained dissolved organic matter, it had a yellow/brown/green hue.

Eventually, the ice shelf collapses. At first, the resulting icebergs look like any other. Once they start melting, though, some of them flip over. The blue iceberg ice combined with the frozen organic matter gives them their green color [source: NY Times].