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Banda Sea and the Deepest Trench in Indonesia

by Reananda Hidayat Permono

Indonesia has many seas with their own depths. However, most of the seas in the eastern part of Indonesia are categorized as deep seas. One of those deep seas, and it’s considered as a rich one, is the Banda Sea.

This article is going to explain about the Banda Sea and the deepest trench in Indonesia.

Characteristics of the Banda Sea

The Banda Sea is not far from Maluku Islands. It’s a part of Indian Ocean but being separated by some islands and Halmahera and Seram Seas. The Banda Sea is surrounded by some islands, such as the Sulawesi Island in the west, Buru and Seram Islands in the north, Watu Bela, Kai, and Aru Islands in the east, and Tanimbar, Babar, Damar, Leti, and Wetar Islands in the south. In the south of Seram Island, you can find Banda Islands as well. The Banda Sea has an area of 500.000 km2. Indonesia is among the 10 countries with the most islands in the world.

Generally, the water temperature of the Banda Sea vary depends on its depth. The deeper the water means the lower water temperature. The Banda Sea has a depth of 600 meters. The depth of 0-5 meter below sea level has an average temperature of 25,70-26,170C. The deeper water will get the average temperature of 25,98-0,160C. The salinity rate of the Banda Sea vary arounf 34,07-34,33 with the average surface salinity of 34,19±0,075. There are some reason why sea water is salty. It’s highly affected by the condition of the Banda Sea as the meeting point of the water from north and from Indian Ocean. Besides our islands, you should also read about Galapagos Island.

Trenches in the Banda Sea

First of all, Indonesian marine has two deep trenches, Banda and Java Trenches, that are located in Indian Ocean. Those two trenches have different depths, around 2.500 meters under sea level in the Java Trenches and more than 7.000 meters in the Banda Trench. In simple words, trench is like a cliff at the sea bottom. The Banda Trench is located to the southeast of Banda Island, or to the west of Kai Islands.

Banda Trench was formed due to the collision of three tectonic plates: Eurasia, Indo-Australia, and Pacific plates. Many earthquakes occurred in this zone, the biggest earthquake even occurred in 1928, it had magnitude of 8,5 Richter scale and produced tsunami wave as high as 1,5 meter.

Until today, there is no specific research about the condition of the Banda Trench. The trench is very dark though, even the sunshine could only penetrate up to 150 meters below the sea surface. It’s not possible for human, even a professional diver, to dive into 7.000 meters below sea level, since it will give high pressure as well, around 700 kg/cm3.

During Dutch colonial around 1929-1930, the Dutch did some marine research using military ship HMS Willebrord Snellius. From this expedition, they could estimate the depth of the Banda Sea and the deepest part of the Banda Trench of 7.440 meters. At that time, they calculated the sea depth using echo sounder tool, it produced a sound wave and record it afterwards after the wave was being reflected at the sea base.

This expedition successfully mapped the Banda Sea, where they found a trench and named it as Weber Trench. Furthermore, they also found North Banda Basin (5.800 meters), South Banda Basin (5.400 meters), and other basins. Unlike a trench with steep creature like cliff, basin is a large valley under the sea. There are 23 types of seas in this world.

There was another research of the Banda Sea. In 1951 an expedition team from Denmark did a research using Galathea ship. They wanted to determine the condition of the Banda Sea and the deepest trench in Indonesia. They used a special tool of steel wire to take some soil samples. It was not only used to analyze the soil though, but also the organism.

From this expedition, it was determined that the base of the Banda Sea contains fine clay, water temperature of 30C, and low rate of oxygen. For the organisms, they got sea cucumber (Paroriza gravei), worm (Macellicephalus hadalis), isopod (Macrostylis hadalis and Leptanthura hendili), and an insect like a spider (Nympon femorale). For science purpose, the mentioned animals are preserved and stored at the Zoological Museum in Copenhagen.

You should also read the characteristics and facts about the Java Sea. Thank you for reading this Banda Sea and the deepest trench in Indonesia article.

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