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
Ontong Java Plateau Ontong Java Plateau The Ontong Java Plateau (OJP) is a huge oceanic plateau located in the south-west Pacific Ocean, north of the Solomon Islands. The OJP was emplaced 120 Ma with a much smaller volcanic event 90 Ma. Two other south-west Pacific plateaus, Manihiki and Hikurangi, now separated from the OJP by Cretaceous ocean basins, are of similar age and composition and probably formed as a single plateau and a contiguous large igneous province together with the OJP. When emplaced this Ontong Java-Manihiki-Hikurangi plateau covered 1% of Earth's surface and represented a volume of of basaltic magma. This "Ontong Java