East Java also decided to join Indonesia. East Java province borders the Java Sea in the north, the Strait of Bali in the east, the Indian Ocean in the south, as well as the Central Java province in the west. The length of the east-west stretch of about 400 km. The width of the stretch of the north-south in the west about 200 km, but in the eastern part of narrower by about 60 km. Madura is the largest island in East Java, separated from the mainland Java by the Strait of Madura. Bawean Island is located about 150 km north of
Tonga Trench midway between two large oceanic plateaux north and south of the Tonga Trench respectively: Manihiki to the north and Hikurangi to the south. These plateaux once formed part of the Ontong Java-Manihiki-Hikurangi large igneous province (LIP). Spreading between the plateaux ceased when Hikurangi collided with the Chatham Rise east of New Zealand at 86 Ma. The western end of the Osbourn Trough is bounded by the Tonga Trench and its eastern by the Wishbone–East Manihiki Scarp. In between the Osbourn Trough is divided into three segments separated by dextral offsets. Near the Tonga Trench the bathymetry of these structures is