Icebergs are large pieces of freshwater ice floating in open water. Icebergs are “born” when they break off from glaciers or ice shelves in a process called “calving.”

Most of the glaciers that calve icebergs can be found along the shores of Greenland. Approximately 10,000 to 15,000 new icebergs break off from these glaciers each year.

Icebergs come in all shapes and sizes. Icebergs the size of a house are considered small.

Icebergs can be much, much bigger. Some icebergs can be as big as an airplane, a building or even an aircraft carrier! The tallest iceberg on record was about 550 feet tall.

So how big does a chunk of ice have to be to be called an iceberg? By definition, icebergs must extend out of the water at least 17 feet and be at least 50 feet long.

As they melt and become smaller, they are sometimes called “growlers” because of the animal-like sounds they make when trapped air escapes as they melt.

While ice cubes floating in your soda seem safe enough, icebergs floating in the ocean can actually be quite dangerous to ships. In fact, an iceberg was responsible for one of the worst maritime disasters of all time.

On the night of April 14, 1912, the RMS Titanic was crossing the North Atlantic when it collided with an iceberg. Although the ship’s lookouts had seen the iceberg with enough advance warning to avoid a head-on collision, the ship still struck the portion of the iceberg that was underwater.

The iceberg punctured the ship’s hull in several places, allowing water to fill several compartments and compromise the ship’s ability to remain afloat. The Titanic sunk early the next morning, resulting in the loss of 1,517 passengers.

The Titanic had been considered “unsinkable” by some because of its advanced design, many safety features and immense size. Despite its impressive construction, it turned out to be no match for the iceberg it encountered that fateful night.

The sinking of the Titanic led to the establishment of the International Ice Patrol, which still patrols the North Atlantic today to keep a lookout for icebergs that might endanger ships at sea.

The iceberg that sank the Titanic was probably extremely big. However, big icebergs are not necessarily more dangerous than smaller ones.

While big icebergs are usually easier for ships to see, smaller icebergs can hide in the ocean’s waves, making them harder to spot and thus much more dangerous.

If you’ve ever heard the phrase, “just the tip of the iceberg,” you might be surprised to learn there’s a lot of truth to it. People use the phrase to mean that what you can see is not all there is.

That’s literally true for icebergs. The higher they extend above the water, the deeper their bases extend below the water. For most icebergs, the part below the water is three to nine times the height above the water.

Despite the danger they pose to ships, icebergs play a key role in nature’s water cycle. As icebergs melt, their water evaporates into the air and forms clouds.

The wind carries some of those clouds over Greenland, where the cold air causes moisture in the clouds to condense and fall as precipitation in the form of snow. Snow builds up on Greenland for thousands of years, forming glaciers.

Gravity forces these massive glaciers toward the sea. As they reach the ocean, the glaciers begin to break off into pieces and fall into the ocean, creating icebergs. As the icebergs travel and begin to melt, the process starts all over again!


22 Join the Discussion

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  1. I have a question. I am doing a research project on penguins and since today’s wonder is on icebergs, do penguins get harmed or effected by icebergs. I know you might not be able to answer but I would appreciate if you would.

    • Hi, Annamarie! What a GREAT question you have about penguins and icebergs! If you click on the link that says “What’s Happening to the Emperor Penguins?” in today’s Wonder, you can find out some interesting facts. We’ve also found another link by the same folks at National Geographic that gives more specific information about penguins and icebergs. Here’s the link:

      Good luck with your project! We know it will be WONDERful! :-)

  2. Hello just wanted to say hey and this is amazing to learn about Icebergs, my class is learning about it and its going great. Keep it up. :D

    • Hi there, Lia! Thanks so much for visiting Wonderopolis today and letting us know how much you enjoyed this Wonder! :-)

    • Thanks for such a nice comment, Brianne! We’ve met so many great new Wonder Friends like you today! Make sure you check back tomorrow for another WONDERful Wonder! :-)

    • You’ll have to check back tomorrow to see for sure, Marie! We like to give little hints, but each new Wonder of the Day is meant to be a surprise (but we think you’re super smart)! :-)

  3. Hello Wonderopolis! I just wanted to say that this wonder really taught me something. It’s not just what the outside looks like, it matters what’s going on inside. Thanks guys! Keep on doing what you’re doing, it’s great and fun to read! :)

    • That’s a GREAT way to think about this Wonder of the Day®, Gracie! We appreciate how your WONDER mind works! We’ll keep WONDERing if you will, too, OK? Thanks so much for hanging out in Wonderopolis and for sharing this super comment with us today! :-)

    • Hi Eriaunna! Thanks for WONDERing with us! We’re so glad that you like the video! Have you seen an iceberg before? Keep WONDERing! :)

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Have you ever wondered…

  • What is an iceberg?
  • Why are icebergs dangerous?
  • How do icebergs play a part in the water cycle?

Wonder Gallery

Try It Out

If you have a hard time imagining how icebergs form and live out their “lives” in the frigid waters of the North Atlantic, explore each step in the Life of an Iceberg through pictures and maps!

When you’re finished exploring the life of an iceberg, make your own! Grab some small plastic toys, a small bucket and a spray mister. Ask someone for help with this activity if you need it.

Using the instructions for the Icebergs Ahead! activity, freeze some small plastic toys in your own homemade iceberg, and then watch it slowly melt to reveal your prizes!


Still Wondering

Emperor penguins are the largest penguin species and the only penguins that spend the winter on the Antarctic ice. In order to find food, mother penguins must travel up to 50 miles to the open sea. Visit National Geographic Xpeditions’ What’s Happening to the Emperor Penguins? lesson to find out how enormous icebergs that have wedged into the ice are making the long journey harder than ever.


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