Indonesia is a very large and diverse country in Southeast Asia and is famous in the world of tourism for its idyllic island of Bali. This Southeast Asian country boasts some of the world's largest and most populated islands. It is the world's largest island nation and is home to a whopping 270 million people making it the fourth most populous country in the world and the country with the highest Muslim population.

The vast areas of Indonesia support some of the world's highest levels of biodiversity - from the orangutans of Borneo (that one can trek and see), to the sunny beaches of Bali, to the giant komodo dragons on the island of Komodo. Here are some of the main islands of Indonesia's 17,000 islands.


Java - The Most Populous

Java is by far the most populous island with 148 million people residing on the island - around 55% of the country's population. That's enough people to make it the most populous island in the world with more people than the British Isles or Japan.

The island is around the size of Arkansas or Alabama (imagine one of those states with nearly half of the US population crammed into them).

  • Population: 148 Million - 55% of the Country
  • Size: 138,800 km2 (53,600 sq mi)

Java is also home to Indonesia's capital city of Jakarta. This has long been the heart of the archipelago and the core of the colonial Dutch East Indies.

There is no shortage of things to see on this volcanically active island (like the massive mud volcano there), the island also has 4 of the country's 8 UNESCO-listed sites to visit. These are:

  • Ujung Kulon National Park
  • Borobudur Temple
  • Prambanan Temple
  • Sangiran Early Man Site

Related: Out Of All The Islands In The Maldives, These Are The Best To Visit

Sumatra - The Second Most Important Indonesian Island

Sumatra is one of the largest islands in the world and stretches close to Singapore. It is the 6th largest island in the world and contains active volcanoes, large plains, lowland swamps, mangrove forests, and (what's left of its) lush rainforests. It is larger than the state of California.

  • Size: 473,481 km2 (182,812 mi.2)
  • Population: 58 Million

Unfortunately, the island has lost around 50% of its rainforests in the last 35 years and many of its unique species are critically endangered.

Some of its more remarkable animals include the Sumatran ground cuckoo, the Sumatran tiger, the Sumatran elephant, the Sumatran rhinoceros, and the Sumatran orangutan. 

New Guinea - The Island With Many Languages

New Guinea is the second-largest island in the world. The linguistic diversity on this island is the definition of mind-boggling. The eastern half of the island is the independent state of Papua New Guinea while the western half is part of Indonesia and is known as Western New Guinea.

The island has the most languages anywhere in the world. The languages in Papua New Guinea are thought to number 826 (the most of any country in the world), with those of Western New Guinea numbering 267.

  • Papua New Guinea: 826 Languages
  • Western New Guinea: 257 Languages
  • Total New Guinea: 1073 Languages (12 Languages Overlapping)

The Torres Strait separates it from Australia. During the last ice age, most of Indonesia's main islands (like Sumatra, Borneo, Java) were connected to Asia. But New Guinea was connected to Australia and is part of the same continental landmass. It is normally grouped with Australia continentally.

  • Size: 785,753 km2 (303,381 sq mi)
  • Population: 5.4 Million (Western New Guinea)

Borneo - The Third Largest Island in The World

Borneo is the third-largest island in the world (after Greenland and New Guinea) and is divided among three different countries - Indonesia, Malaysia, and Brunei. Indonesia controls around 73% of the island, with Malaysia controlling around 26%. The remaining 1% is controlled by the oil-rich independent country of Brunei.

Borneo is home to one of the oldest rainforests in the world and is famous for its orangutans and other wildlife.

Related: Caribbean Islands: A Guide To Each Major Destination (So You Can Choose Easily)

Bali - The Holiday Destination

Bali is the main tourist destination in Indonesia and is comparatively a small island. It is east of Java and west of Lombok and tourism makes up around 80% of its economy. Bali has much of the best tourist infrastructure and many people who visit this island don't bother to explore any further.

  • Size: 5,780 km2 (2,230 sq mi)
  • Population: 4.3 Million

It is the only Hindu majority province in otherwise Muslim majority Indonesia with 87% people of being Hindu.

It is also in the Coral Triangle - an area with the highest biodiversity of marine species, especially fish and turtles. It also boasts the Subak irrigation system - a UNESCO-listed site.

Sulawesi - The Odd Looking Island

Sulawesi is a very odd-shaped island and the 11th largest island in the world. It was previously known as Celebes and is one of the often forgotten islands of Indonesia that is worth seeing.


  • Size: 180,680.7 km2 (69,761.2 sq mi)
  • Population: 20 Million

Next: Philippines Vs. Indonesia: Where You Should Go, And Why