Java and Bali to the east. Borneo lies to the north and Christmas Island is to the south. It is the world's 13th largest island. Java is surrounded by the Java Sea to the north, Sunda Strait to the west, the Indian Ocean to the south and Bali Strait and Madura Strait in the east. Java is almost entirely of volcanic origin; it contains thirty-eight mountains forming an east–west spine that have at one time or another been active volcanoes. The highest volcano in Java is Mount Semeru (). The most active volcano in Java and also in Indonesia is Mount
Tonga Trench Tonga Trench The Tonga Trench is an oceanic trench located in the south-west Pacific Ocean. It is the deepest trench of the Southern Hemisphere and the second deepest on Earth. The fastest plate tectonic velocity on Earth occurs as the Pacific Plate is being subducted westward in the trench. When the Apollo 13 mission was aborted in 1970 following an explosion in an oxygen tank, the radioisotope thermoelectric generator broke up in the atmosphere and the heat source plunged in or near the Tonga Trench. Atmospheric and oceanic monitoring indicate no release of nuclear fuel has occurred. The deepest point