Sumatra

Sumatra (also spelled Sumatera) is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia (two larger islands, Borneo and New Guinea, are partially in Indonesia), and the sixth largest island in the world (approximately 470,000 km²).Sumatra was known in ancient times by the Sanskrit names of Swarnadwīpa ("Island of Gold") and Swarnabhūmi ("Land of Gold"), due likely to the gold deposits of the island's highlands.Arab geographers referred to the island as Lamri (Lamuri, Lambri or Ramni) in the 10-13th centuries, in reference to a kingdom near modern day Banda Aceh which was the first landfall for traders. Late in the 14th century the name Sumatra became popular, in reference to the kingdom of Samudra which was a rising power. European writers in the 19th century found that the indigenous inhabitants did not have a name for the island.

Papua

IRIAN JAYA (PAPUA)
Widely known also as Papua, Irian Jaya is Indonesia's largest and easternmost province covers the western half of the world’s second largest island. A central east-west mountain range forms the backbone of Irian Jaya and Papua New Guinea, and it reaches its maximum altitude in the west, with Puncak Jaya as the highest peak, about 5050 metres. This and other peaks of Irian Jaya have permanent snowfields and small glaciers. Weather wise; climate of the coastal area is hot, humid and rainy most of the year, while the highlands have warm to hot days and cool to very cold evenings, depending on the altitude. Plenty of rain falls in the highland, and the season vary from valley to valley. May to July is the driest time and the most favorable time for trekking usually from January to March as the climate is not too hot and the trails also not muddy. 
 
Papua province has extremely different character to other parts of provinces in Indonesia particularly their communities. The Papuan are distinctly different from the Malayan people of other Indonesian islands in the west, they are more close to their neighboring Papua New Guinea people with dark skinned, wooly haired, the men heavily bearded, their facial features reminiscent of the Australian Aborigines. The people of the island can be divided into more than 250 sub-groups, including the Marind-anim, Yah’ray, Asmat, Mandobo, Dani and Afyat. Those living in the central island still maintain their customs and traditions, nearly untouched by outsider influences.

Sulawesi

The island formally known as the Celebes, Sulawesi, is not unlike the other larger islands in the archipelago as far as travelling is concerned – you need at least three months to explore it and even then you will only be scratching the surface. However, it is possible to cover the main areas and major attractions in a few weeks. Sulawesi has an area of around 172,000 square km Indonesia’s third-largest island and the world’s eleventh-largest island.Geographically, Sulawesi has everything to offer the traveller with spectacular mountains ideal for a casual climb and a coastline that is as beautiful as you will find anywhere in the world. Add to that the numerous lakes, dense jungles and friendly people then it is understandable that Sulawesi is one of the few islands where you can experience cultural and marine diversity, the latter offering some of the best dive sites in Indonesia. The largest cities on the island are Makassar, on the South-western coast of the island, and Manado on the northern tip.

Kalimantan

Borneo, of which Indonesian Kalimantan covers two-thirds, is a single, vast-ecosystem in which the thick, exuberant forest that covers the world's third largest island acts as an enormous sponge. 

Formed over millions of years, the rainforest of Kalimantan is almost completely self-sustaining, requiring little more than water from the skies to survive. The soil on which the forest grows is thin and poor, and rather than drawing nutrients from the ground, it feeds on its own debris, recycling the nutrients contained in the rotting compost on the floor. Trees soar upwards, reaching a height of seventy meters or more, providing support for vines, creepers and orchids, and creating a dense canopy of leaves that protects the layer of humus from being washed away by the fierce tropical storms. While the thick cover of the forest blocks direct sunlight, rotting leaves and root mass store water from the rains, releasing it gradually during the dry season. Thus, the forest also creates and maintains the dark, warm, dank environment essential for its own continuous growth and that of the life within it.

Java

Java (Indonesian: Jawa) is an island of Indonesia and the site of its capital city, Jakarta. Once the centre of powerful Hindu kingdoms, Islamic sultanates, and the core of the colonial Dutch East Indies, Java now plays a dominant role in the economic and political life of Indonesia. Home to a population of 130 million in 2006, it is the most populous island in the world, ahead of Honshū, the main island of Japan. Java is also one of the most densely populated regions on Earth.

Formed mostly as the result of volcanic events, Java is the 13th largest island in the world and the fifth largest island in Indonesia. A chain of volcanic mountains forms an east-west spine along the island. It has three main languages, and most residents are bilingual, with Indonesian as their second language. While the majority of Javanese are Muslim, Java has a diverse mixture of religious beliefs and cultures.

Indonesia

The Republic of Indonesia (Indonesian: Republik Indonesia), is a transcontinental country in Southeast Asia and Oceania. Comprising 17,508 islands, it is the world's largest archipelagic state. With an estimated population of around 237 million people, it is the world's fourth most populous country and the most populous Muslim-majority nation; however, no reference is made to Islam in the Indonesian constitution. Indonesia is a republic, with an elected legislature and president. The nation's capital city is Jakarta. The country shares land borders with Papua New Guinea, East Timor and Malaysia. Other neighboring countries include Singapore, the Philippines, Australia, and the Indian territory of the Andaman and Nicobar Islands.

The Indonesian archipelago has been an important trade region since at least the seventh century, when the Srivijaya Kingdom traded with China and India. Local rulers gradually adopted Indian cultural, religious and political models from the early centuries CE, and Hindu and Buddhist kingdoms flourished. Indonesian history has been influenced by foreign powers drawn to its natural resources. Muslim traders brought Islam, and European powers fought one another to monopolize trade in the Spice Islands of Maluku during the Age of Discovery. Following three and a half centuries of Dutch colonialism, Indonesia secured its independence after World War II. Indonesia's history has since been turbulent, with challenges posed by natural disasters, corruption, separatism, a democratization process, and periods of rapid economic change.