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Indonesia - Sea of thousand islands

Java-, Celebes-, Banda-, Arafura- and Timor Seas

Indonesia’s Lesser Sunda Islands sparkle like green gems against the sapphire-blue waters of the Indian Ocean and Flores, Banda, Sawu, and Timor Seas. These islands form the southern border of Indonesia with Australia and stretch for 1,200 kilometers from the western island of Lombok on the left to the eastern tip of Timor, the largest island in the image. (Photo: Jeff Schmaltz, MODIS Rapid Response Team, NASA/GSFC).

The Java-, Timor- and Arafura Seas are widely extremely shallow and flat tropical shelf seas located in southeastern Asia and north of the Australian continent. The seas are situated 5 to 15 degrees south of the equator. The very deep Banda- and Celebes Seas are located few degrees south and north of zero degree latitude, respectively. The southeastern Asian waters represent the oceanographic interface between the Indian Ocean and the Pacific Ocean.


The climatic conditions are tropical throughout the entire region. All seas are influenced by summer and winter Monsoons. Regional wind and current patterns are also dominated by the seasonal wind systems. River discharge and other terrestrial impacts are important factors for the hydrographic system of the individual seas and their marine productivity. The warm and moist summers cause high surface water temperatures, while slightly cooler winters let drop the water temperature rather insignificantly. Heavy rainfalls are associated with tropical cyclones and thunderstorm activity.


The region hosts roughly 20,000 islands. Many of the islands provide white sand beaches, coconut palms fringing the shore, multi colored coral reefs and abundant shoals of unique, colorful fish stocks.


Besides trade and regional transport, fishing is one of the main economic sources of the region. Fisheries in the open water of the seas mainly concentrate on Pacific mackerel, tuna and different sardine species. Most of the catches are composed of young fish with an average age of less than one year. Coastal trawling for prawns and shrimps supplies the marine export-industry.


A silver band of sunglint highlights internal waves in the Celebes, Molucca, and Banda Seas around Indonesia in this Moderate Resolution Imaging Spectroradiometer (MODIS) image. Sunglint occurs when the sun reflects off the surface of the water directly into MODIS’ “eye,” creating a glare. If the ocean were perfectly smooth, the sunglint would be a bright circular reflection of the sun. But since the sea is rough, and not a perfect mirror, the circle is distorted into the band visible here. The ocean is made up of different layers of water that have different densities. When the dense lower layer is dragged against a rough surface on the sea floor, it ripples. The resulting wave travels between two layers of the ocean. Unlike surface waves, internal waves can travel for long distances and can stretch up to tens of kilometers in length. (Photo: Jeff Schmaltz, MODIS Rapid Response Team, NASA/GSFC)

Oil and gas fields occur in different parts of the region, and particularly the geology of the Arafura Sea suggests that a petroleum system should be actively charging reservoirs underneath that shelf sea. More newly emerging oil exploration areas covering the southeastern Asian region promise future petroleum production and increasing incomes.


Marine debris is increasingly impacting on marine species, habitats and coastal communities within the southeastern Asian region. Debris like discarded fishing nets, plastic bags or even complete television sets can maim and kill wildlife - including threatened and protected species like marine turtles, dugongs and dolphins - through entanglement and strangulation. Waste that has washed ashore can also interfere with nesting birds and turtles, while large nets floating in the sea pose additional navigation hazard. Evidence suggests that a large proportion of the debris washed ashore is from prawn and fish trawling operations.


Besides the many native tribes before, from European point of view the Portuguese first visited the southeastern Asian region at the beginning of the 16th century. The Dutch expelled the Portuguese later in the 17th century and conquered different natives groups in the Makasar War (1666 to 1669).



Java Sea


The Java Sea is extremely flat and shallow throughout. It is connected to the Celebes Sea to the northeast by the Makassar Strait and adjoins the Flores Sea to the east. To the northwest, the Java Sea is connected to the South China Sea via the Karimata Strait, and abuts the Bali Sea to the south.


The circulation and hydrography of the Java Sea are determined by the annual cycle of Monsoon winds, with currents flowing westward from June to August and eastward during the rest of the year.


The island of Java south of the sea represents a tectonic feature called ”island arc”. An island arc is a set of islands formed by submarine volcanoes that grow above a subduction zone. The volcanoes may grow from the sea floor to as much as thousands of meters above sea level. In the case of Java Island the submarine volcanoes formed a large single island.



Celebes Sea


The Celebes Sea is a deep basin with narrow, shallow shelves steeply breaking towards greater water depths. The sea is part of the Austral-Asian Mediterranean Sea between the Sulu Sea to the north and Moluccan Sea to the southeast. The Makassar Strait connects the Celebes Sea to the Java Sea and water exchange with the open Pacific Ocean takes place via a ridge system between the Celebes basin and the Philippine Trench.


During the summer, the Monsoon winds create a surface current directed from the north towards the Makassar Strait in the south. This current regime is largely maintained through the winter, although westward currents are additionally found in the Celebes Sea.


On Sulawesi north of the Celebes Sea, Asian and Australian elements are mixed in the fauna, which includes swine-resembling species, an endemic small wild ox, some rare species of parrot, and many crocodiles. Furthermore, there is a great variety of whales and dolphins in the Celebes Sea: 26 cetaceans species out of 78 existing in the World live here.


Valuable stands of timber cover much of the island and many forest products are exported. Mineral resources include nickel, gold, diamonds, sulfur, and low-grade iron ore. The mountainous terrain and the narrow coastal plains limit agriculture. Thus, many people seek their income from the sea and from tourism, which was developed in the 1990s. Sulawesi is a major source of copra, corn, rice, cassava, yams, tobacco, and different spices.



Banda Sea


The Banda Sea is a regional sea in the Austral-Asian Archipelago consisting of several deep basins and troughs separated by sills. The extremely narrow shelves of surrounding islands are mostly about 500 meter deep and steeply break to the deep sea.


Reefs and strong coastal currents represent hazards to shipping. The Banda Sea is also an area of extensive upwelling of colder and nutrient-rich water masses. The upwelling occurs during the southwestern Monsoon.



Arafura Sea


The Arafura Sea is part of the southeastern Austral-Asian Mediterranean Sea located between the Timor and Coral seas, and separating Australia from New Guinea. The sea is an extended shelf sea ranging from 50 to 80 m water depth and contains several islands of Indonesia. Due to many islands and shallows the Torres Strait to the east is a treacherous ship passage.


The shelf areas are rich in shrimps, while the deeper waters have rich tuna resources. The rapid development of trawl fisheries in the region was strongly influenced by the demand of the global market.


A program forced by the World Wildlife Fund seeks to conserve freshwater- and coastal wetlands and surrounding landscapes in the Arafura Sea region of northern Australia, southern Papua New Guinea and southwest Papua, Indonesia.



Timor Sea


The Timor Sea is widely a shallow and flat regional sea located in the Austral-Asian Mediterranean Sea. Towards the north, the sea steeply slopes towards the deep Timor Trough. The sea consists of the Timor Strait to the north and the Sahul Shelf to the south.


The Timor Sea region is influenced by the Pacific-Indian Ocean throughflow, which contributes to the westward flowing South Equatorial Current.


Tropical cyclones form south of the equator in the area of the eastern Indian Ocean and in the Timor and Arafura Seas.




Modern Piracy


Looking back from today, piracy in ancient times had a somewhat romantic touch of ”adventure”, of ”cruising the World Ocean” and of ”taking from the rich, giving to the poor” like Robin Hood and his faithful did in the Sherwood Forest. During the 17th and 18th century, worldwide piracy flourished wherever trade routes passed through narrows or island groups. The ancient pirates attacked with small, wooden sailing boats and quickly returned to the coastal hiding places after successful robbery.


Today, piracy is still a worldwide maritime problem along all heavily frequented ship routes. Major regions of recurrent armed robberies or even piracy are around the Bay of Bengal, the Gulf of Guinea and parts of South America, however, the most dangerous portion of the World Ocean still are the southeastern Asian seas. In 2001, 150 of the worldwide roughly 300 pirate attacks were committed in southeastern Asian waters with the Malacca Strait (36 attacks) and the Flores Sea (91 attacks) being the most dangerous sea routes.


Sometimes, modern pirates try to be rather tricky than violent and claim to be from the coastguard or the navy in order to stopping the chased vessel. However, most pirate attacks in recent days are committed by masked criminals, which are heavily armed with knifes and automatic weapons and using speedboats. Pirates chase the vessels partly for hours and try to maneuver alongside in order to enter the ship. In case of ”success”, the pirates steel stores and lower them to the speedboats, ”collect” valuables from the crew, and even take hostages or the whole ship.


In 2001, pirates killed a total of 21 crew-members and ships' passengers, and 210 were taken hostage. All but one of the murders were committed in Asian waters. Evidently, individual pirates do not have the resources to organize attacks and, thus, the hijackings have to be regarded as the work of organized crime rings operating in the coastal waters.


The three littoral States of the Malacca Strait (Indonesia, Malaysia and Singapore) implemented a coordinated patrol and other counter-measures in the region in 1992. Today, the global piracy statistics are compiled by the Piracy Reporting Center in Kuala Lumpur. Cargo ships and tankers are advised to maintain anti-piracy watches and report all piratical attacks. Like in former times, today piracy is still under severe penalty in many countries - until death penalty.



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