Geography Indonesia is the largest archipelago (1,904,686 square kilometers) in the world, straddling the equator between the Asian and Australian continents, extending 5,110 kilometers from east to west and 1,888 kilometers from north to south, and comprising the five main island Java (home to about 70% of the country's population), Sumatra, Kalimantan, Sulawesi and Irian Jaya. Altogether 17,508 islands of varying size and more than seven million square kilometers of ocean are the geographical superlatives of this country. The Archipelago divided into three groups. The islands of Java, Sumatra and Kalimantan, and the small islands in-between, lie on the Sunda Shelf which begin on the coasts of Malaysia and Indo-China, where the sea depth does not exceed 700 feet, Irian Jaya which is part of the island of New Guinea, and the Aru islands lie on the Sahul Shelf, which stretches northwards from Australian coast. Here the sea depth is similar to that of the Sunda Shelf.
Located between these two shelves is the island group of Nusa Tenggara, Maluku and Sulawesi, where the sea depth reaches 15,000 feet. Coastal plains have been developed around the islands of Sumatra, Java, Kalimantan and Irian Jaya. The land area is generally covered by thick tropical rain forest, where fertile soils are continuously replenished by volcano eruptions like those on the island of Java. The terrain varies considerably from one part of Indonesia to another with much of the country being mountainous and approximately two thirds being covered in forest or jungle. The Archipelago of Indonesia is situated on the matching point of the two world greatest volcanic ranges, the Mediterranean from the west and Circum Pacific from the northeast, by which the volcanic pattern, physiography, and geomorphology of the archipelago are strongly influenced. Many rivers flow throughout the country. They serve as useful transportation routes on certain islands, for example, the Musi, Batanghari, Indragiri and Kampar rivers in Sumatra; the Kapuas, Barito, Mahakam rivers in Kalimantan; and the Memberamo and Digul rivers in Irian Jaya. On Java rivers are important for irrigation purposes.
Indonesian time zones As of January 1, 1988, Indonesia's three time zones have been changed as follows:
Western Indonesian Standard Time is GMT plus 7 hours (meridian 105"E), covering all provinces in Sumatra and Java, and the provinces of West and Central Kalimantan.
Central Indonesian Standard Time is GMT plus 8 hours (meridian 120"E), covering the provinces of East and South Kalimantan. all provinces in Sulawesi and the provinces of Bali, West and East Nusa Tenggara and East Timor.
Eastern Indonesian Standard Time is GMT plus 9 hours (meridian 135"E), covering the provinces of Maluku and Irian Jaya.
For People on Central European Time, such as in Vienna, this means the following: Western Indonesian Standard Time is +6 hours (+5 in summer = daylight savings time). For example: 12.00 noon in Vienna corresponds to 18.00 in Jakarta (17.00 in summer). Central Indonesian Standard Time is +7 hours (+6 in summer) Eastern Indonesian Standard Time is +8 hours (+7 in summer)