Islands of the World

What Is an Island?

Picture a piece of land with the blue sea all the way around it — no bridge, no path, just water on every side. That is an island.

Islands come in every size you can imagine. Some are so tiny that only a few palm trees and a strip of sand fit on them. Others are huge, with mountains, forests, rivers and big cities. There are islands in warm tropical seas, islands in cold northern oceans, and islands in the middle of rivers and lakes.

The largest island in the world is Greenland, a cold, icy land in the far north. (Australia has water all around it too, but it is so enormous that we call it a continent, not an island.) In this book we will find out how islands are made, why their animals are so special, and how people live surrounded by the sea. Grab your sun hat — let's go island-hopping!

Islands Made by Fire

Where do islands come from? One amazing way an island is born is from a volcano.

Deep under the sea, the floor of the ocean has volcanoes too. When one erupts, it pours out hot, melted rock called lava. The lava cools and turns hard, piling up layer upon layer. If the volcano keeps erupting for long enough, the pile grows taller and taller until — at last — it pokes up above the waves. A brand-new island is born, made entirely of cooled volcanic rock!

The beautiful islands of Hawaii, far out in the Pacific Ocean, were all made this way. So was Iceland, a northern island that still has bubbling hot springs and active volcanoes today. To learn more about these fiery mountains, you can read All About Volcanoes.

Islands Made by Tiny Animals

Here is something amazing: some islands are built not by fire, but by tiny living creatures!

In warm, shallow seas live little animals called coral polyps. Each one builds a hard, stony home around itself. When millions of them live and grow together over thousands of years, their stony homes pile up to make a coral reef. Sometimes the reef grows so high that it reaches the surface and sand gathers on top, making a low, sandy island called a coral island or atoll.

Many of the picture-postcard islands in the warm parts of the world — ringed by clear water and white beaches — are coral islands. It is wonderful to think that a whole island can be built by creatures smaller than your fingernail. You can meet more reef-builders in Our Amazing Oceans.

Islands Made by the Sea

There is a third way islands are made, and it is gentler than fire or coral. Sometimes a hill or a piece of high land becomes an island simply because the water around it rises.

Long ago, when the world was colder, much more water was frozen into ice. The seas were lower, and some islands were joined to the mainland by dry land you could walk across. As the ice melted and the sea rose, the low land flooded, leaving the higher parts poking up as separate islands.

The islands of Britain, off the coast of Europe, were once joined to the mainland this way. Long ago you could have walked there; now you must cross the sea. So the same piece of land can be part of a continent one age and an island the next, depending on how high the sea is.

Special Animals of the Islands

Islands are wonderful places for nature, and they often have animals found nowhere else on Earth. Why?

The answer is the sea. Because an island is cut off by water, its animals are kept apart from the rest of the world for a very long time. Slowly, over thousands and thousands of years, they change little by little to suit their island home, until they become quite different from their relatives elsewhere. Animals or plants that live in just one place and nowhere else are called endemic.

The island of Madagascar, off the coast of Africa, is famous for animals like lemurs that live there and nowhere else in the wild. The Galápagos Islands have giant tortoises and unusual birds found only there. Sadly, island animals can also be in danger, because they have nowhere else to go if their home is harmed — so islands are very precious places to protect.

Living on an Island

People have lived on islands for thousands of years, and island life has its own special rhythm. The sea is always nearby — for food, for travel, and for fun.

Because the water is all around, boats and ships are very important. On some islands, people travel between villages by boat the way other people use cars. Long ago, brave Pacific Islander sailors crossed enormous distances of open ocean in canoes, finding tiny islands by reading the stars, the waves and the flight of birds — without any maps at all.

Many island countries are made of lots of islands together. Indonesia in Asia is made of thousands of islands, and Japan is made of several large ones plus many small ones. On these islands, ferries, bridges and planes help everyone stay connected across the sea.

Famous Islands Around the World

Let's take a quick boat trip to meet a few famous islands.

• Greenland is the world's largest island — cold, icy and mostly covered in a giant sheet of ice.
• Madagascar, near Africa, is home to lemurs and chameleons found nowhere else.
• Iceland, in the north, was made by volcanoes and has hot springs, waterfalls and glaciers.
• Hawaii, in the middle of the Pacific Ocean, is a chain of warm volcanic islands famous for beaches and surfing.
• Britain, off the coast of Europe, is a busy island once joined to the mainland.

Every island has its own story, its own animals and its own people — and there are thousands more waiting to be discovered.

What We Learned

What a journey across the seas! We learned that an island is land with water all around it, and that islands come in every size, from tiny sandy specks to giant Greenland.

We discovered the three main ways islands are born: by volcanoes building up from the seabed, by tiny coral animals piling up reefs, and by the rising sea flooding the low land. We found out why island animals are so special and often endemic, like the lemurs of Madagascar. And we saw how people live on islands, travelling by boat across the waves.

Islands remind us that our watery planet is dotted with thousands of little worlds, each one different from the rest.

Ready for more sea adventures? Dive beneath the waves in Our Amazing Oceans, or discover the lands these islands belong to in The Seven Continents.