Oceanic trench the level of the surrounding oceanic floor. The greatest ocean depth measured is in the Challenger Deep of the Mariana Trench, at a depth of below sea level. Oceanic lithosphere moves into trenches at a global rate of about 3 km/yr. There are approximately of convergent plate margins, mostly around the Pacific Ocean—the reason for the reference “Pacific-type” margin—but they are also in the eastern Indian Ocean, with relatively short convergent margin segments in the Atlantic Ocean and in the Mediterranean Sea. Globally, there are over 50 major ocean trenches covering an area of 1.9 million km or about 0.5%
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