Major Islands and Peninsulas

An island is a piece of land completely surrounded by water and smaller than a continent, while a peninsula is a piece of land surrounded by water on three sides and joined to a larger land mass. In brief: the largest island in the world is Greenland (about 2.17 million km²), followed by New Guinea, Borneo and Madagascar. The Arabian Peninsula (about 3.2 million km²) is generally regarded as the largest peninsula. Islands are formed by volcanoes, coral growth, rising sea levels and tectonic movement, and peninsulas by tectonic and erosional processes.

Islands and peninsulas are important for biodiversity, shipping routes and human settlement. This guide defines islands and peninsulas, lists the major examples, compares the largest islands in a table, works through size comparisons, outlines their history and corrects common mistakes.

What are the major islands?

Islands range from tiny sand banks to huge land masses. By convention, Australia is counted as a continent and not an island, so the largest island is Greenland (about 2.17 million km²), a self-governing territory of Denmark, with an ice sheet over about three-quarters of it. Next are New Guinea (about 0.79 million km², shared by Papua New Guinea and Indonesia), Borneo (about 0.74 million km², shared by Indonesia, Malaysia and Brunei), Madagascar (about 0.59 million km²), Baffin Island (about 0.51 million km², in Canada), Sumatra (about 0.47 million km²), Honshu in Japan, Victoria Island and Great Britain (each around 0.21–0.23 million km²), and Ellesmere Island. Islands by origin: continental islands (once part of the mainland, such as Great Britain and Madagascar), volcanic islands (such as Hawaii and Iceland) and coral islands (atolls of the Pacific and Indian Oceans). Island groups are called archipelagos, such as Indonesia, the Philippines and Japan.

What are the major peninsulas?

Peninsulas are named from the Latin paene insula (almost an island). The largest by area is usually the Arabian Peninsula (about 3.2 million km²), which contains Saudi Arabia, Yemen, Oman, the United Arab Emirates, Qatar, Kuwait and Bahrain. Others: the Indian subcontinent (sometimes called a peninsula, though it is joined to Asia by a very wide base), the Indochina Peninsula in Southeast Asia, the Scandinavian Peninsula (Norway and Sweden), the Labrador Peninsula in Canada, the Iberian Peninsula (Spain and Portugal), the Anatolian Peninsula (Asian Turkey), the Korean Peninsula, the Italian Peninsula, the Balkan Peninsula, the Kamchatka Peninsula in Russia, the Yucatán Peninsula in Mexico, and Florida. Many peninsulas are joined to the mainland by an isthmus, a narrow neck of land.

Why are islands and peninsulas important?

Islands often have unique ecosystems because isolation leads to the evolution of species not found elsewhere (endemic species), such as the lemurs of Madagascar. They are vulnerable to invasive species and, for low-lying islands, to rising sea levels. Strategic islands and peninsulas have been used as trading posts, naval bases and ports; peninsulas have long coastlines and so many harbors, and shape sea routes, such as around the Cape of Good Hope or past Singapore at the tip of the Malay Peninsula. Island states (such as Japan, Iceland, the Philippines and small Pacific states) depend on the sea for fishing, trade and tourism.

Largest islands compared

Worked example: comparing sizes

1. Greenland and Great Britain: 2.17 ÷ 0.209 = about 10.4, so Greenland is about ten times the size of Great Britain.
2. Greenland and Africa: Africa (30.4 million km²) is 30.4 ÷ 2.17 = 14 times as large as Greenland, although on a Mercator map Greenland looks similar in size to Africa.
3. Island or continent? Australia, with about 7.69 million km², is 7.69 ÷ 2.17 = 3.5 times as large as Greenland, which is the reason, together with its geology as a continental plate, that it is classed as a continent.
4. Ice cover: the Greenland ice sheet covers about 1.7 million km², which is 1.7 ÷ 2.17 = 78 percent of the island.
5. Borneo and Madagascar: 0.74 ÷ 0.59 = 1.27, so Borneo is about 27 percent larger than Madagascar.
6. Peninsula and island: the Arabian Peninsula (3.2 million km²) is 3.2 ÷ 2.17 = 1.5 times the area of Greenland.

How have islands and peninsulas shaped history?

The Mediterranean peninsulas of Greece and Italy and islands such as Crete, Sicily and Cyprus were the centers of ancient civilizations and trade. Polynesian navigators settled the remote islands of the Pacific over many centuries, using sophisticated knowledge of the sea. European powers took islands and peninsulas as bases for trade and empire, such as Singapore, Malta and Hong Kong. The Iberian Peninsula was the starting point of many voyages of exploration in the 15th and 16th centuries. In the modern era, island nations face challenges such as sea-level rise, and Greenland’s melting ice is important for global sea level.

Which mistakes are common?

Mistake 1: Calling Australia the largest island

By convention, it is a continent. The largest island is Greenland.

Mistake 2: Confusing a peninsula with an isthmus

A peninsula is a piece of land surrounded by water on three sides; an isthmus is the narrow strip of land that joins two larger land areas.

Mistake 3: Assuming that all islands are small

Some, such as Greenland, New Guinea and Borneo, are larger than many countries.

Mistake 4: Treating all islands as formed in the same way

Islands can be continental, volcanic or coral, each with a different origin and different features.