The Japan Trench is an oceanic trench, a part of the Pacific Ring of Fire, in the floor of the northern Pacific Ocean off northeast Japan. It extends from the Kuril Islands to the Bonin Islands and is 9,000 metres (29,500 ft) at its deepest. It is an extension of the Kuril-Kamchatka Trench to the north and the Izu-Ogasawara Trench to its south with a length of 800 km (500 mi).
This trench is created when the oceanic Pacific plate subducts beneath the continental Okhotsk Plate. The subduction process causes bending of the downgoing plate, creating a deep-sea trench. Continuing movement on the subduction zone associated with the Japan Trench is one of the main causes of tsunamis and earthquakes in northern Japan, including the megathrust Tōhoku earthquake and resulting tsunami that occurred on 11 March 2011.